Toowoomba Landfill Cell

The Toowoomba Waste Management Centre, located on Hermitage Road in Cranley, Toowoomba, is a critical landfill site operated by the Toowoomba Regional Council (TRC). DECC was engaged as the Principal Contractor to execute the vertical expansion of the existing landfill Cell A2. This project was essential to provide additional capacity for waste disposal, fully utilising the available air space within the landfill.

The project involved the construction of a vertical expansion for Cell A2 at the Toowoomba Waste Management Centre. The work was divided into three main stages, each critical to the successful completion of the project:

Stage 1: Profiling/Preliminary Earthworks and Liner Material Acquisition
Stage 2: Installation of Landfill Gas Infrastructure (LGI)
Stage 3: Construction of Vertical Expansion

The vertical expansion of Cell A2 at the Toowoomba Waste Management Centre was completed successfully, providing the Toowoomba Regional Council with additional landfill capacity and ensuring the continued operation of the waste management facility. The project met all environmental and safety standards, demonstrating DECC’s capability to manage complex civil works in challenging environments.

Bulk Excavation: Conducted 30,000m³ of bulk excavation, including the careful removal and relocation of waste materials to a designated stockpile area. This process involved the use of heavy machinery to manage large volumes of earth and waste, ensuring the site was adequately prepared for subsequent construction activities.

Subgrade Preparation: Performed comprehensive cut-to-fill operations, ensuring the subgrade was accurately shaped and conditioned to meet engineering specifications. This involved the strategic excavation and placement of soil to create a stable foundation, essential for supporting the structural integrity of the landfill’s expansion.

Collaboration with LGI: Worked closely with landfill gas infrastructure (LGI) specialists to install an advanced gas collection system immediately following the completion of subgrade preparation. This collaboration ensured that the gas management infrastructure was seamlessly integrated into the landfill’s design, enhancing environmental protection measures.

Compacted Clay Liner (CCL) Placement: Installed 20,500m² of compacted clay liner (CCL) as a critical component of the landfill's containment system. The CCL was meticulously compacted to create a low-permeability barrier, effectively preventing leachate migration and ensuring long-term environmental safety.

Geomembrane and Geotextile Installation: Placed 20,300m² of LLDPE geomembrane liner, alongside the installation of cushion, separation geotextile, and biaxial geogrid layers. These materials were precisely positioned to enhance the landfill’s structural stability and prevent contamination, forming a multi-layered protective system.

General and Engineered Fill: Placed and moisture-conditioned approximately 6,500m³ of both general and engineered fill materials. This process involved selecting and processing fill to achieve optimal compaction and stability, providing a robust foundation for the landfill expansion while ensuring long-term durability.

Leachate Collection System: Constructed a leachate collection sump, installed perforated leachate pipes, and a riser pipe, followed by the placement of drainage gravel. These elements were integral to the leachate management system, designed to efficiently collect and transport leachate, preventing environmental contamination.

Stormwater Management: Constructed perimeter sediment control channels and implemented erosion protection measures to manage stormwater runoff effectively. This involved engineering solutions to direct and contain surface water, minimizing erosion risks and protecting surrounding environments from potential water damage.