In early 2009 a large rainfall event occurred in north-west Queensland which resulted in large stormwater flows in the vicinity of the Lady Annie copper mine. As a consequence, substantial stormwater flows occurred through the sulphuric acid ore processing facility, with the result that the pollution control systems and tailing ponds were overloaded. In addition, parts of the membranes lining the tailing ponds were dislodged by the stormwater flows. As a consequence, a substantial amount of contaminated water exited the mine site, with resultant contamination of a very large area of land.
Later, and because of the limited resources of the mine operator [viz: CopperCo], the mine site was shut down, and CopperCo put into liquidation. Subsequently, the insurer for the mine operator requested SCE to advise on the cause of the contaminated water release and resultant contamination of land.
The SCE investigations revealed that:
- The cause of the contaminated water release was failure to install an effective diversion drain around the ore processing facility which was located within an area subject to flooding during heavy rainfall.
- The civil engineering designer of the ore processing facility had misunderstood the implications of large rainfall events in north-west Queensland, and consequently recommended against the construction of an effective diversion drain around the ore processing facility.
- It was probable that the civil engineering designer could be held responsible for the damage.
Despite this advice, and partly because of the potential cost of litigation against an overseas based civil engineer, the insurer decided to commercially resolve the issue with the liquidator of CopperCo.
Later, and because it was necessary to remediate both the mine site and large area of contaminated ground, the Queensland government ended up arranging for the site to be remediated at the cost of about $11 mill. Click here for more information on the remediation works carried out.