Tailings pond rehabilitation project and effluent management system upgrade, Baldivis

In 1969, Western Mining Corporation Limited constructed a tailings pond in Baldivis, 7 km from the Company's Kwinana Nickel Refinery, to store solid and liquid wastes from the refinery. In March 1979, it was discovered that the tailings pond was leaking ammonium sulphate solution to the groundwater resulting in contamination of the bottom third of the groundwater body (aquifer).

Currently, the proponent is recovering contaminated groundwater to manage the spread of the plume. However, at the same time it still continues to use the leaking tailings dam. ln order to correct this situation the proponent proposes to:

• recover and treat liquid effluent from the tailings pond;
• stop the disposal of refinery liquid effluent to ttle existing tailings pond;
• increase the rate of recovery of contaminated groundwater;
• significantly upgrade its wastewater treatment plant to handle liquid effluent from the refinery and liquid effluent recovered from the tailings pond, in addition to contaminated groundwater;
• construct a new double-lined effluent disposal pond structure comprising two compartments for evaporation of effluent resulting from the upgraded wastewater treatment plant, and one compartment for intermittent disposal of solid residue If required;
• rehabiiitate the existing tailings pond to ensure its structural and environmental integrity;
• continue monitoring the extent and rnovernent of the groundwater plume and the condition of vegetation fringing Lake Cooloongup and the undertaking of necessary preventative and remedial action if required;
• maintain the above activities until the groundwater contamlnation plume has been satisfactorily recovered and the existing tailings pond has been rehabilitated. (WMC's commitments will apply in the event of continued operation of the nickel refinery at current production levels or an increase or decrease in production levels or closure of the refinery); and
• rehabilitate the existing leaking tailings dam.