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Detailed cell design documentation in Arriga

Detailed cell design documentation in Arriga

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CLIENT

Remondis

SECTOR

Waste

SOLUTIONS

Geo-environmental engineering

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Colin Stapleton

Senior Principal

Overview

Senversa was commissioned by the Springmount Waste Management Joint Venture (SWMJV) to prepare detailed design documentation for the construction of Cell 6 at the Springmount Waste Management Facility (SWMF) in Arriga, Queensland. The project was initiated to ensure continuity of waste disposal services in the Cairns Region, with Cell 6 providing an estimated three years of operational capacity.

Scope

The scope of consultancy work included the development of a comprehensive design report, technical specifications, construction drawings, and supporting engineering assessments. The design was informed by site-specific conditions including topography, geology, hydrology, and climate data, and incorporated regulatory requirements from the Queensland Department of Environment, Tourism, Science and Innovation (DETSI) and Environmental Authority (EA) permit BRID00026.

Key design elements included:

A composite liner system comprising a 2.0 mm LLDPE geomembrane, geosynthetic clay liner (GCL), and compacted clay-rich fill.
A leachate collection system with perforated HDPE pipes embedded in 300 mm of drainage aggregate, connected to Cell 5 infrastructure.
Groundwater depressurisation system with primary and secondary drainage pipes to maintain liner separation and prevent uplift.
Embankment geometry with internal and external slopes of 1V:3H and crest widths accommodating anchor trenches, stormwater drains, and light vehicle access.
Bulk earthworks balancing cut and fill volumes, with an estimated net cut of 7,600 m³.
Stormwater management infrastructure including perimeter drains and chutes designed for 10% and 1% AEP rainfall events.

Safety-in-design features addressing construction and operational risks, including traffic management, landfill gas exposure, and contaminated material handling.

Senversa also conducted detailed assessments for slope stability, liner seepage, veneer stability, and anchor trench performance. The design was supported by HELP modelling for leachate generation and rational method hydrology for stormwater infrastructure sizing. The final design achieved compliance with DETSI guidelines and EA permit conditions, while optimising airspace efficiency and environmental protection.

Challenge

One of the key challenges was managing the site's steep topography and shallow rock levels, which constrained excavation depth and required strategic grading to maintain floor geometry. The design addressed this by incorporating shared infrastructure with Cell 5 and optimising bund geometry to reduce earthworks quantities.

Groundwater management posed another significant challenge due to seasonal perched flows and subgrade defects. Senversa resolved this through a depressurisation system with adaptive trenching and automated monitoring to detect potential liner leakage.

Designing the liner system required careful consideration of strain, seepage, and stability. The inclusion of a geogrid reinforcement layer was critical to achieving acceptable factors of safety for veneer stability under static, seismic, and construction loading conditions. Anchor trench dimensions were calculated to resist tensile forces from wind uplift and veneer loading.

Stormwater management infrastructure was designed to accommodate runoff from future cell developments, with erosion protection measures specified for high-velocity flows. The use of RipRap and vegetated channels ensured compliance with QUDM and DETSI guidelines.

Safety-in-design assessments identified high residual risks related to vehicle interaction, landfill gas exposure, and contaminated material handling. These were mitigated through design controls and construction management requirements, including traffic plans, PPE protocols, and intrinsically safe equipment.

Outcome

The Cell 6 design successfully delivered a robust, compliant, and environmentally sound solution tailored to the unique conditions of the Springmount site.

The final design achieved a gross airspace capacity of approximately 510,000 m³, supporting SWMJV’s operational needs for up to three years and aligning with long-term landfill development plans. Overall, the project demonstrated Senversa’s capability to deliver technically rigorous and regulatory-compliant landfill designs under complex site conditions, contributing to the sustainable operation of SWMF.