Mining Water Stewardship
Sep 7th, 2016
Mining water stewardship can avoid the industry running into a global crisis. The Global Risk Report of World Economic Forum (WEF) has indeed identified water as one of the top five risk generating scenarios that could most impact society over the next decade.
Mining Water Stewardship
The International Council for Mining and Metals (ICMM) has developed guidance documents on responsible stewardship. Mining water stewardship is not only altruistic. Mining operators that do not address water issues may have unacceptable returns on investments.
Many studies, however, do consider water merely as a process consumable and do not adhere to mining water stewardship principles.
Causes of the problem
Closure planning is rarely considered a priority and discounted cash-flow models (NPV) hide the true cost of closure (distant failures).
Recent studies show that ineffective planning and management of water through mines’ life cycle decreased real returns due to impacts. For example, water problems reportedly partly caused the Bento Rodrigues 2015 Samarco Fundão dam disaster.
That is certainly not big news as if we look at some statistics of causes of failure (World-wide 1910-2009 data). From the 145 dams reported as failed we can see that beside:
- Foundation Subsidence (12 failures),
- Structural Defects (12 failures), and
- Management (21 failures)
all the other causes are at partly linked to a water mismanagement. That amounts approximately to 70% of the reported major world tailings dam failures. Incidentally, we will discuss causality of failures at our next courses in (A path to zero failures in tailings facility) Keystone (Colorado) Oct 2nd, 2016 and (Risk Assessment, Decision Making and Management of Mine Waste Facilities) Vancouver Nov 13th, 2016 (B.C.)
Solutions to the problem
In order to evaluate a system Success Criteria have to be defined, for example:
- Meet effluent limits established by regulatory agencies for all anticipated contaminants.
- Not cause acute fish toxicity – even a single rainbow trout kill- during the standard 96 hrs lethal toxicity test.
- Ability to adapt to changes in feed water composition and finally
- minimize the generation of waste residues that constitutes potential long term liability.
One then need to functionally analyze the system processes in such a way to consider all the macro elements of the system, for example:
- Reagent supply & delivery to reactor(s)
- Solid/liquid separation
- Effluent polishing
- Solids handling/disposal and finally
- Solids recycle & conditioning
After careful hazard identification for each of those macro element one has to calculate the risks and compare to the pre-selected success criteria. Indeed, this delivers a risk landscape description.
If unacceptable risks show up, then one has to add mitigations and perform a new round of risk evaluations until all the risks become acceptable.
Conclusions to the problem
A risk landscape analysis, based on various time horizons, monitoring and adaptation will finally help stakeholders understand the variability of risks on all the different aspects.
Or as the Auditor General for the Province of British Columbia recommended after Mount Polley tailings dam failure. “1.10 Risk-based approach. We recommend that government develop a risk-based approach to compliance verification activities, where frequency of inspections are based on risks, such as industry’s non-compliance record, industry’s financial state, and industry’s activities (e.g., expansion), as well as risks related to seasonal variations.”
Tagged with: 2015 Samarco, discounted cash flow models (NPV), ICMM, International Council for Mining and Metals, Mining Water Stewardship, Mount Polley tailings dam failure, Risk-based approach
Category: Consequences, Risk analysis, Risk management, Tolerance/Acceptability