The wastewater treatment lagoons serving the Olympic Dam mine site had reached the end of their workable life as they did not have sufficient volume for the site population and there were known to be sinkholes in the base of the secondary lagoon. As part of the selection phase for the upgrade project, BHP Billiton was seeking an options study from which a preferred upgrade solution could be selected for further development.
Tonkin Consulting reviewed previous reports on the system, attended site to inspect the infrastructure and discussed with BHP Billiton their expectations for the upgrade. The deliverable for the project was an options report detailing the findings of the investigations.
Following on from this options report, Tonkin Consulting was engaged to carry out water quality testing on available wastewater, potable water and process water samples in order to further investigate reuse options.
Given there was initially no inflow data available, the design flows for the upgrade were based on literature values, with allowances made for future population increases. Assumptions were adopted for influent quality given the known water usage habits on the mine site.
Four main options were identified for treatment and disposal of wastewater, ranging from disposal by evaporation through to high level treatment and reuse in mine operations. The options were developed with consideration for Department of Health and EPA requirements.
Indicative estimates were determined for both capital and operational costs. The advantages and disadvantages of each option were discussed in relation to cost, safety, constructability, operability, environmental considerations, reuse benefit and land usage. The options report delivered reported on all these findings and provided recommendations for progressing the project through to the definition phase.