Cover System Design Guided by Multi-Criteria Analysis (MCA)

Okane provided closure planning services at a decommissioned gold mine in Queensland, aiming to develop suitable cover system options for the tailings storage facility (TSF) rehabilitation. Cover system design options were required to meet established regulatory requirements and performance criteria for a low-permeability layer cover system

The project involved:

• A site visit to collect samples for geotechnical and geochemical analysis;
• Completing a material characterization program;
• Undertaking numerical modelling to assess the base case conceptual cover system design against several alternatives that included low permeability layers; and
• Completing a multi-criteria analysis (MCA) supported by a cost-benefit analysis (CBA) for comparison of cover system alternatives to assess the cost versus performance of each alternative.

The analysis recommended modifying the original cover system design. The alternative design reduced the overall cover thickness, included a low-permeability layer, and implemented a single capillary break. The alternative design was optimized for both cost and performance in comparison to the original design while meeting regulatory compliance requirements.