Most mining projects assess needs for water treatment. But how do you determine if treatment is required or which is the best treatment option for your project?
Typically one conducts a Life Cycle Cost analysis of the available water management and treatment options to determine the most cost-effective solution meeting site specific requirements. While Life Cycle Cost is a useful starting point, at BQE Water we believe that Risk Adjusted Life Cycle Cost is much more instructive.
The Risk Adjusted Life Cycle Cost starts with the Life Cycle Cost and applies factors to account for how a water treatment system integrated into the overall water management plan adds or removes risks, in particular long-term or systemic risks. By accounting for risks in a comprehensive and pragmatic manner, water treatment can be designed to mitigate risks and improve the overall project economics in a sustainable way.
Below we look at several examples of risk factors relevant to assessing the Risk Adjusted Life Cycle Cost of mine water treatment.
- Residue. Different water treatment methods generate different types and volumes of residue that can vary wildly in their management requirements. Large volumes of brine from reverse osmosis is much more costly to manage than a small quantity of stable solid residue that can be mixed with tailings or residue that is suitable for offtake or resale.
- Adaptability. Mines are long lived projects that go through many phases. It is important to design water treatment systems that are suitable not only for current needs but also the needs of the future. System demands may change due to mine expansion or closure plans, larger catchment areas, regulatory requirements or discrepancies between geochemical/hydrological modeling and reality.
- Water Storage. Tailings ponds filled with water can represent very large liabilities for the mine owner. Water treatment for safe and controlled discharge is preferable to building a water storage dam higher and is far less expensive than cleanup, remediation and lawsuits resulting from a tailings dam breach or spill.
One methodology for assessing the Risk Adjusted Life Cycle Costs of these risk factors and other uncertainties and variabilities for the projected service life is the Comprehensive Decision Analysis/Economic Safety Margin (CDA/ESM) developed by Riskope, a firm specializing in quantified risk management services. Their methodology involves combining risk severity with risk probability in order to assign concrete monetary value to risk. The application of CDA/ESM methodology to mine water treatment was explored in a presentation to Environment Canada, “Water Treatment Alternatives Life Cycle Assessments – Risk Based Decision Making.”
Analyzing water treatment with Risk Adjusted Life Cycle Cost in mind allows the mine owner to better manage and mitigate long-term risks to protect shareholder value, corporate reputation and stakeholder partnerships. Further, this approach can also be invaluable during the project permitting stage when discussing the mitigation of project risks with government regulators and public stakeholders.
Patrick Littlejohn, MaSC, PhD, EIT