TAILING DAMS RISK ANALYSIS AND MANAGMENT Pavel Danihelka

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TAILING DAMS RISK ANALYSIS AND MANAGMENT Pavel Danihelka Eva Červeňanová UNECE WORSHOP ON TDS,

TAILING DAMS RISK ANALYSIS AND MANAGMENT Pavel Danihelka Eva Červeňanová UNECE WORSHOP ON TDS, YEREVAN, November 2007

CONTENT: • • Examples of historical accidents Introduction to risk theory Risk analysis principles

CONTENT: • • Examples of historical accidents Introduction to risk theory Risk analysis principles Basics of application of risk analysis to tailing dams safety • Conclusion UNECE WORSHOP ON TDS, YEREVAN, November 2007

EXAMPLES OF HISTORICAL ACCIDENTS At least 221 serious tailing dams accidents reported by UNEP*:

EXAMPLES OF HISTORICAL ACCIDENTS At least 221 serious tailing dams accidents reported by UNEP*: Mine name/ Location Incident Date Impact Baia Mare, Romania 30. 01. 2000 100, 000 m 3 cyanide contaminated water with some tailings released Baia Borsa, Romania 10. 03. 2000 22, 000 t of tailings contaminated by heavy metals released Merriespruit, South Africa 22. 02. 1994 17 deaths, 500, 000 m 3 slurry flowed 2 km * http: //www. mineralresourcesforum. org/docs/pdfs/Bulletin 121. PDF UNECE WORSHOP ON TDS, YEREVAN, November 2007

Major tailing dams review – cont. Mine name/ Location Incident Date Impact Buffalo Creek,

Major tailing dams review – cont. Mine name/ Location Incident Date Impact Buffalo Creek, USA 26. 02. 1972 125 deaths, 500 homes destroyed Mufilira, Zambia 25. 09. 1970 89 deaths, 68, 000 m 3 into mine workings Omai, Guyana 19. 08. 1995 4. 2 million m 3 cyanide slurry released Placer, Philippines 02. 09. 1995 12 deaths, 50, 000 m 3 released Los Frailes, Spain 24. 04. 1998 released 4 -5 million cubic meters of toxic tailings slurries Stava, Italy 19. 07. 1985 269 deaths, tailings flowed up to 8 km Aitik mine, Sweden 09. 08. 2000 1. 8 million m 3 water released UNECE WORSHOP ON TDS, YEREVAN, November 2007

History of major tailing dams accidents Source: „ICOLD Bulletin 121“ UNECE WORSHOP ON TDS,

History of major tailing dams accidents Source: „ICOLD Bulletin 121“ UNECE WORSHOP ON TDS, YEREVAN, November 2007

Case study: BAIA MARE January 30, 2000 in Baia Mare (Romania) the biggest freshwater

Case study: BAIA MARE January 30, 2000 in Baia Mare (Romania) the biggest freshwater disaster in Central and Eastern Europe. Nearly 100, 000 m 3 of cyanide and heavy metal-contamined liquid spilled into the Lupus stream, reaching the Szamos, Tisza, and finally Danube rivers and killing hundreds of tones of fish and poisoning the drinking water of more than 2 million people in Hungary. UNECE WORSHOP ON TDS, YEREVAN, November 2007

LOS FRAILES April 25, 1998 tailings dam failure of the Los Frailes lead-zinc mine

LOS FRAILES April 25, 1998 tailings dam failure of the Los Frailes lead-zinc mine at Aznalcóllar near Seville, Spain, released 4 -5 million cubic meters of toxic tailings slurries and liquid into nearby Río Agrio, a tributary to Río Guadiamar. The slurry wave covered several thousand hectares of farmland, and it threatens the Doñana National Park, a UN World Heritage Area. UNECE WORSHOP ON TDS, YEREVAN, November 2007

STAVA On July 19, 1985, a fluorite tailings dam of Prealpi Mineraia failed at

STAVA On July 19, 1985, a fluorite tailings dam of Prealpi Mineraia failed at Stava, Trento, Italy. 200, 000 m 3 of tailings flowed 4. 2 km downstream at a speed of up to 90 km/h, killing 268 people and destroying 62 buildings. The total surface area affected was 43. 5 hectares. UNECE WORSHOP ON TDS, YEREVAN, November 2007

AITIK On September 8, 2000, the tailings dam of Boliden's Aitik copper mine near

AITIK On September 8, 2000, the tailings dam of Boliden's Aitik copper mine near Gällivare in northern Sweden failed over a length of 120 meters. This resulted in the spill of 2. 5 million cubic meters of liquid into an adjacent settling pond. Boliden subsequently released 1. 5 million cubic meters of water from the settling pond into the environment to secure the stability of the settling pond. UNECE WORSHOP ON TDS, YEREVAN, November 2007

VARIABILITY OF CAUSES OF ACCIDENT • • Inadequate management Lack of control of hydrological

VARIABILITY OF CAUSES OF ACCIDENT • • Inadequate management Lack of control of hydrological system Error in site selection and investigation Unsatisfactory foundation, lack of stability of downstream slope • Seepage • Overtoping • Earthquake MAIN ROOT CAUSE: RISK ANALYSIS AND MANAGEMENT NEGLECTED UNECE WORSHOP ON TDS, YEREVAN, November 2007

Distribution of causes of tailing dams accidents Source: ICOLD Bulletin 121 UNECE WORSHOP ON

Distribution of causes of tailing dams accidents Source: ICOLD Bulletin 121 UNECE WORSHOP ON TDS, YEREVAN, November 2007

VARIABILITY OF CONSEQUENCES • Flooding, wave of slurry • Contamination of surface water, living

VARIABILITY OF CONSEQUENCES • Flooding, wave of slurry • Contamination of surface water, living organisms (biota), intoxication • Drinking and irrigation water contamination (surface) • Drinking and irrigation water (underground) contamination • Soil contamination • As consequence of 2), 3), 4)ad. 5 : Food chain contamination » FREQUENTLY TRANSBOUNDARY EFFECT UNECE WORSHOP ON TDS, YEREVAN, November 2007

Conclusion: • Tailing dam is a risky installation able to cause major accident and

Conclusion: • Tailing dam is a risky installation able to cause major accident and so we have to treat it as major risk UNECE WORSHOP ON TDS, YEREVAN, November 2007

2. INTRODUCTION TO RISK THEORY • Definition of – Hazard – Risk • Risk

2. INTRODUCTION TO RISK THEORY • Definition of – Hazard – Risk • Risk and its quantification (measurement) • Principles of risk reduction/management UNECE WORSHOP ON TDS, YEREVAN, November 2007

DEFINITION OF TERMS SOURCE OF DANGER = POTENTIAL TO CAUSE DAMAGE UNECE WORSHOP ON

DEFINITION OF TERMS SOURCE OF DANGER = POTENTIAL TO CAUSE DAMAGE UNECE WORSHOP ON TDS, YEREVAN, November 2007

RISK = PROBABILITY x GRAVITY OF ACCIDENT (EVENT) UNECE WORSHOP ON TDS, YEREVAN, November

RISK = PROBABILITY x GRAVITY OF ACCIDENT (EVENT) UNECE WORSHOP ON TDS, YEREVAN, November 2007

RISK DANGEROU SITY IDENTICAL RISK DIFFERENT DIFFERENCE: MANAGEMENT OF RISK UNECE WORSHOP ON TDS,

RISK DANGEROU SITY IDENTICAL RISK DIFFERENT DIFFERENCE: MANAGEMENT OF RISK UNECE WORSHOP ON TDS, YEREVAN, November 2007

FLUX OF DANGER Initial event Other conditions Source system Flux of danger Target system

FLUX OF DANGER Initial event Other conditions Source system Flux of danger Target system DOMINO EFFECT: INITIAL EVENT SYSTEM 1 SYSTEM 2 SYSTEM 3 CATASTROPHE Example: Stava accident UNECE WORSHOP ON TDS, YEREVAN, November 2007

 • Flux of danger: Ø Movement of material Ø Flux of energy Ø

• Flux of danger: Ø Movement of material Ø Flux of energy Ø Flux of information • Targets system: Ø Population around tailings dam Ø Environment • Surface water • Underground water • Soil • Living organisms Ø Material and financial losses (direct) Ø Functioning of enterprise (including indirect losses) UNECE WORSHOP ON TDS, YEREVAN, November 2007

 • Sources of danger: – Having potential (energy) to cause damage – Having

• Sources of danger: – Having potential (energy) to cause damage – Having potential to weaken structure, resistance, resilience of our system (tailing dam and its environment) • Direct to dam stability • Indirect including human error • To consequences UNECE WORSHOP ON TDS, YEREVAN, November 2007

 • RISK MATRIX A – banal case B – frequent accident with low

• RISK MATRIX A – banal case B – frequent accident with low consequences (minor injury, small contamination, . . . ) PROBABILITY QUANTIFICATION OF RISK B C A D C – disaster with high probability (walking in minefield) D – disaster with low probability (nuclear power plant, major incident) GRAVITY UNECE WORSHOP ON TDS, YEREVAN, November 2007

 • Acceptability of risk PROBABILITY NON ACCEPTABLE ACTION NECESSARY RISK MITIGATION ACCEPTABLE ACTION

• Acceptability of risk PROBABILITY NON ACCEPTABLE ACTION NECESSARY RISK MITIGATION ACCEPTABLE ACTION VOLUNTARY CONDITIONALLY ACCEPTABLE GRAVITY UNECE WORSHOP ON TDS, YEREVAN, November 2007

ACCEPTABILITY OF RISK • Decision is socio-politic, not scientific • Decision should include all

ACCEPTABILITY OF RISK • Decision is socio-politic, not scientific • Decision should include all stakeholders • All types of risk should be evaluation together UNECE WORSHOP ON TDS, YEREVAN, November 2007

How to decrease risk? UNECE WORSHOP ON TDS, YEREVAN, November 2007

How to decrease risk? UNECE WORSHOP ON TDS, YEREVAN, November 2007

RISK ANALYSIS PROCESS Feedback and control Selection of sources of danger Scenarios proposal Risk

RISK ANALYSIS PROCESS Feedback and control Selection of sources of danger Scenarios proposal Risk assessment Goals setting Barriers of prevention ETA FTA AMDEC FMEA HAZOP WHAT-IF Etc. Risk management IMPACT Residual risk PROBALITY TECHNICAL ORGANISATION BARIERS BARRIERS UNECE WORSHOP ON TDS, YEREVAN, November 2007

SOURCES OF DANGER Ø Direct to dam stability: • • Active environment (rain, snow,

SOURCES OF DANGER Ø Direct to dam stability: • • Active environment (rain, snow, freeze…) Earthquake Geological conditions Domino effect Ø Indirect to dam (including human error): • • • Wrong conception Construction failure Material failure Bad maintenance Lack of control Ø To consequence: • • Water and sludge movement Mechanical contamination by solid particles Chemical toxicity / ecotoxicity Radioactivity UNECE WORSHOP ON TDS, YEREVAN, November 2007

SCENARIO PROPOSAL • All plausible scenario should be involved in preliminary conspiration • All

SCENARIO PROPOSAL • All plausible scenario should be involved in preliminary conspiration • All stages of life-time must be considered • Those having minor impact omitted • Similar combined to groups • Described as combination of events in time • Finally, we are able to compare limited number of scenarios only UNECE WORSHOP ON TDS, YEREVAN, November 2007

TOOLS HELPING TO DEFINE SCENARIO • • • Examples of past accidents Near-misses and

TOOLS HELPING TO DEFINE SCENARIO • • • Examples of past accidents Near-misses and accidents on site Control list WHAT-IF ETA FTA AMDEC FMEA HAZOP Etc. UNECE WORSHOP ON TDS, YEREVAN, November 2007

Past accidents analysis • In site – during all life of it • In

Past accidents analysis • In site – during all life of it • In similar places you operate, including near-misses. Mind the necessity of reporting. • In mine industry generally – TAILINGS DAMS, RISK OF DANGEROUS OCCURRENCES, Lessons learnt from practical experiences, ICOLD- UNEP 2001, Bulletin 121, ISSN 0534 -8293 – APELL for Mining: Guidance for the Mining Industry in Raising Awareness and Preparedness for Emergencies at Local Level, Technical report No. 41, UN Publications 2001, ISBN 92 -807 -2035 UNECE WORSHOP ON TDS, YEREVAN, November 2007

SCENARIO DESCRIPTION CAUSES CONSEQUENCES 1 2 „TOP“ EVENT 3 4 (DAM DESTRUCTION) 5 6

SCENARIO DESCRIPTION CAUSES CONSEQUENCES 1 2 „TOP“ EVENT 3 4 (DAM DESTRUCTION) 5 6 7 SCENARIO 1 SCENARIO 2 EACH SCENARIO NUMBERED UNECE WORSHOP ON TDS, YEREVAN, November 2007

RISK ASSESMENT: • FREQUENCY x CONSEQUENCES (IMPACT) FREQUENCY: • From past accidents (high degree

RISK ASSESMENT: • FREQUENCY x CONSEQUENCES (IMPACT) FREQUENCY: • From past accidents (high degree of uncertainty) • From initial events frequency and FTA by boolean algebra • Avoid omitting of low frequency events (not to limit only to 100 -year water or earthquake) • Human factor extremely important UNECE WORSHOP ON TDS, YEREVAN, November 2007

Frequency of „ 100 year“ flooding UNECE WORSHOP ON TDS, YEREVAN, November 2007

Frequency of „ 100 year“ flooding UNECE WORSHOP ON TDS, YEREVAN, November 2007

One mythus: „We operate it long time without accident, so safety is prooved“ UNECE

One mythus: „We operate it long time without accident, so safety is prooved“ UNECE WORSHOP ON TDS, YEREVAN, November 2007

CONSEQUENCES: • Consequences to human lives, health and well being. Evaluation of consequences with

CONSEQUENCES: • Consequences to human lives, health and well being. Evaluation of consequences with stakeholders necessary • Direct costs (remediation, compensation, . . . ) • Social disturbance • Consequence to environment – short time and long time impacts • Economical consequences and operability • Indirect costs UNECE WORSHOP ON TDS, YEREVAN, November 2007

Costs of Failure Physical failure: recent large failures $30 to $100 million in direct

Costs of Failure Physical failure: recent large failures $30 to $100 million in direct costs Environmental failure: some recent clean-up liabilities to several $100’s of millions Closure liability: some recent examples in $ 500 milon to $ 4 billion range Industry/investor impacts: Shareholder value losses and industry imposed constraints and costs amounting to many billions of dollars UNECE WORSHOP ON TDS, YEREVAN, November 2007

CONSEQUENCES II: • The scales of consequences should be defined before analysis is done

CONSEQUENCES II: • The scales of consequences should be defined before analysis is done (4 -6 grades) • All possible targets should have the same scales of consequences (e. g. Grade X is comparable in all target systems) • The most serious consequence is selected • Internal values of society/enterprise become to be clarified UNECE WORSHOP ON TDS, YEREVAN, November 2007

Severity of impact – an example (source: Robertson Geo. Consultants Inc. ) UNECE WORSHOP

Severity of impact – an example (source: Robertson Geo. Consultants Inc. ) UNECE WORSHOP ON TDS, YEREVAN, November 2007

RISK ASSESSMENT PROBABILITY Following frequency and gravity, scenarios are put to the risk matrix

RISK ASSESSMENT PROBABILITY Following frequency and gravity, scenarios are put to the risk matrix 1 5 2 4 3 7 6 GRAVITY UNECE WORSHOP ON TDS, YEREVAN, November 2007

GOALS SETTING: Non-axeptable (red zone) scenarios: immediate action PROBABILITY Conditionally acceptable (yellow zone) scenatios:

GOALS SETTING: Non-axeptable (red zone) scenarios: immediate action PROBABILITY Conditionally acceptable (yellow zone) scenatios: action envisaged 1 5 2 4 3 6 2 7 7 GRAVITY UNECE WORSHOP ON TDS, YEREVAN, November 2007

BARIERS OF PREVENTION / PROTECTION Initial event BARRIER Other conditions Source system REMOTION OF

BARIERS OF PREVENTION / PROTECTION Initial event BARRIER Other conditions Source system REMOTION OF SOURCE INITIAL EVENT SYSTEM 1 Flux of danger BARRIER Target system BARRIER PROTECTION OF TARGET SYSTEM 2 BARRIER OF FLUX DOMINO EFFECT UNECE WORSHOP ON TDS, YEREVAN, November 2007 SYSTEM 3 CATASTROPHE

SAFETY MANAGEMENT • Prevention part (even three part of bow-tie diagram) • Emergency preparedness

SAFETY MANAGEMENT • Prevention part (even three part of bow-tie diagram) • Emergency preparedness UNECE WORSHOP ON TDS, YEREVAN, November 2007

NEAR MISSES: „HUNTING FOR DEVIATIONS“ ELIMINATED CATASTROPHE BIG ACCIDENTS / LOSSES SMALL ACCIDENTS/ LOSSES

NEAR MISSES: „HUNTING FOR DEVIATIONS“ ELIMINATED CATASTROPHE BIG ACCIDENTS / LOSSES SMALL ACCIDENTS/ LOSSES DEVIATIONS UNECE WORSHOP ON TDS, YEREVAN, November 2007

Emergency preparedness • Preparedness to accident, even with low probability • Training and not

Emergency preparedness • Preparedness to accident, even with low probability • Training and not only desktop one • Information of all potentially involved • Crisis management including training • Open and honest communication with municipalities, emergency response teams, government bodies (inspection…) • Communication with media UNECE WORSHOP ON TDS, YEREVAN, November 2007

RECOMMENDATIONS 1) Detailed site investigation by experienced geologists and geotechnical engineers to determine possible

RECOMMENDATIONS 1) Detailed site investigation by experienced geologists and geotechnical engineers to determine possible potential for failure, with in situ and laboratory testing to determine the properties of the foundation materials. 2) Application of state of the art procedures for design. 3) Expert construction supervision and inspection. 4) Laboratory testing for “as built” conditions. 5) Routine monitoring. 6) Safety evaluation for observed conditions including “as built” geometry, materials and shearing resistance. Observations and effects of piezometric conditions. 7) Dam break studies. 8) Contingency plans. 9) Periodic safety audits UNECE WORSHOP ON TDS, YEREVAN, November 2007

And something for thinking… UNECE WORSHOP ON TDS, YEREVAN, November 2007

And something for thinking… UNECE WORSHOP ON TDS, YEREVAN, November 2007

DO WE REALLY NEED ACCIDENT PREVENTION? • • You've carefully thought out all the

DO WE REALLY NEED ACCIDENT PREVENTION? • • You've carefully thought out all the angles. You've done it a thousand times. It comes naturally to you. You know what you're doing, its what you've been trained to do your whole life. • Nothing could possibly go wrong, right ? UNECE WORSHOP ON TDS, YEREVAN, November 2007

THINK AGAIN! UNECE WORSHOP ON TDS, YEREVAN, November 2007

THINK AGAIN! UNECE WORSHOP ON TDS, YEREVAN, November 2007

THINK AGAIN! UNECE WORSHOP ON TDS, YEREVAN, November 2007

THINK AGAIN! UNECE WORSHOP ON TDS, YEREVAN, November 2007

 • Thank you for your attention ! UNECE WORSHOP ON TDS, YEREVAN, November

• Thank you for your attention ! UNECE WORSHOP ON TDS, YEREVAN, November 2007