Performance objectives and indicators of Tailings dams with Space observation
Sep 4th, 2019
Some of our readers are all about Performance objectives and indicators of Tailings dams with Space observation. They work in the imagery and space observation industry. As a result they asked some questions about our book Tailings Dams Management for the Twenty-First Century.
Google Earth, image date 10/4/2018
We thought it would be interesting to publish the Q/A session.
Q/A session on Performance objectives and indicators of Tailings dams with Space observation
Q1: With reference to your book can you tell me whether it includes information which would allow me to go from specific measurements that our clients do to the current risk level at a tailings facility.
A1: yes, the book has specific information enabling to go from the specific measurements to the current risk level at a tailings facility. That includes a relative failure diagnostic, prediction and a possible bench-mark against world wide performance of tailings dams portfolio.
Q2: For example MAC (Mining Association of Canada) says that it is best practice for an EoR (Engineer of Record) to monitor “performance objectives and indicators”. However it doesn’t say what these are.
A2: no wonder! They haven’t done the research we have performed, so they talk about “principles”, but no fact/model driven data on Tailings dam and their failures!
Q3: Three “indicators” companies monitor are volume of water, proximity of the water to the tailings embankment and volume of new material deposited.
A3: these are intuitively interesting. However, we do not know of anyone that has been capable of linking them objectively and numerically in easy ways to the probability of failure. In particular, we have data that show that raising velocity and height do not correlate well to the probability of failure. We do consider the proximity of water and the lack of water balance management as important factors in our analyses. But there are numerous others we consider. In fact there are thirty different factors we consider in ORE2_Tailings! They range from:
- construction/investigation (investigations and testing), (see Oboni, F., Oboni, C., A systemic look at tailings dams failure process, Tailings and Mine Waste 2016, Keystone, Colorado, USA, October 2-5, 2016);
- design (materials, cross section, seismic, liquefaction);
- maintenance and management (Wet spots on the D/S face; Streaming, Ponding at toe, water balance, etc.).
Q4: Does your book discuss which “indicators” one should monitor?
A4: yes, it does. Note, however, that many factors we cited earlier, are not the result of physical monitoring but the result of the “history” of the dam. That is results of decisions made before its design and construction. Among these, notably, any
- divergence from plans, and
- lack of documentation.
Q5: If so is there any discussion (in the book) of how to determine the relative importance of specific measurements? For example – is it sufficient to only measure water volume change or only water proximity to embankment?
A5: yes, the book discusses what needs to be monitored. Because it is absolutely not sufficient to only measure water volume change and beach lengths. Indeed, as we said earlier our tailings dam model take into account thirty variables to deliver a failure prediction.
Q6: In your summary of the book you mention InSAR which can be used to measure ground movement rate (velocity) of embankments. Do you discuss any other measurements ?
A6: yes, we do. Note however, the book is not focused on monitoring techniques.
Closing remarks
You and your clients may find it interesting to read a couple papers:
F. Oboni, C. Oboni, R. Morin, Innovation in Dams Screening Level Risk Assessment, ICOLD 2019, Ottawa, June 2019
F.Oboni, C.H.Oboni, R.Morin, S.Brunke, C.Dacre., Space Observation, Quantitative Risk Assessment Synergy Deliver Value to Mining Operations & Restoration, (see the presentation) Rouyn-Noranda, 2018, Symposium on Mines and the Environment, Rouyn-Noranda, Québec, June 17 to 20, 2018
C., Oboni, F., Oboni, Triaging 50 km of dykes, Geohazards 7, Canmore AB, June 3-6, 2018
We are of course available to show you and your clients the capabilities of our application named ore2_tailings.
Tagged with: MAC Mining Association of Canada, Performance objectives, space observation, Tailings Dams
Category: Consequences, Crisis management, Mitigations, Optimum Risk Estimates, Probabilities, Risk analysis, Risk management, Tolerance/Acceptability
It is the very Monitoring Techniques or lack thereof that is implicated in any recent failure. Commensurate with that is the act of humans with available, archived, or active near-real-time data. With no recipe of practice like RiskReduction Monitoring (SM), and an active link to recent inspections, or not, ongoing volumetric and specific gravity measure (Tailings Reflective Index) and actual data from recurrent and active <24 days (twice monthly) satellite radar and in-situ instrument measurements) you are just playing games. Perhaps modeling with data as recent as? if any actually from your site or with As-Built data. guesstimates …pure and simple…may be good ones but …
I remain confounded by consultants and practitioners' fear of actual data from which to engage regularly. It is a clear and egregious lack of diligence, applied safety, and any pretense for a sustainable practice.
There are ready, affordable solutions — that need ready, available, professional on-site staff or consultants with experience in any tools use from the last 20 years.