Mining Disaster -Mount Polley-

Presented by

BOUDARINE Asmoune

BENDIMERAD Chaouki

Tinasoa Arimanana Rado

Master STPE – 2015/2016

Presentation Plan 1/ Different steps of mining exploitation 2/ The unused Tailings

3/ The environmental hazard 4/ Mount Polly Situation 5/ Mount Polly disaster

6/ Analysis of the event (The breach) 7/ The likely Causes 8/ Consequences of this disaster

9/ conclusions 10/Advises

11/ presentation sources

o When metal is mined, the rock

is separated into three

categories.

o The ore is then milled, usually

on-site, to separate the

metallic minerals (e.g. metal

sulfides) from lower value

minerals like silicates and iron

sulfide (pyrite.) tailings

o What remains after processing

is called : tailings

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1/ Different steps of mining exploitation

Tailings are disposed of in special impoundments meant to

prevent pollution from escaping

Tailings Dam

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2/ The unused Tailings

• Human production of mine tailings has

increased by several orders of magnitude in

the modern age.

• Many mine tailings do not become

appreciably safer over time, if stored properly,

and therefore must stored for an indefinite

period using current technology.

To store for an indefinite period using current

technology present two mean problems for

Human society in current time :

- Environment Pollution, including rivers and

lakes…etc.

- The dam failure, where the taillings are stored.

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3/ The environmental hazard

4/ Mount Polley Situation 4

A tailings pond for the Mount Polley mine in B.C. had its dam

break on Aug. 4, 2014, spilling its toxic contents into Polley

Lake.

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5/ Mount Polley disaster

• Video show

*****Aerials of destruction caused by Mount

Polley Mine tailings pond breach.wmv

********

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• Based on monthly tailings data

collected from the Mount Polley

Mining Company, at the time of

the disaster the dam held over 10

million cubic meters of

supernatant water, and about 87

million tonnes of tailings.

• The breach of the tailings pond

released 10-billion litres of mining

wastewater and 4.5-million cubic

metres of metals-laden fine sand

into local waterways.

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6/ Analysis of the event (The breach

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A Cross-section showing the different sections of the dam

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• Upstream method of embankment construction

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• foundation Instability,

• slope instability,

• overtopping,

• mine subsidence,

• unusual rain,

• snow melt,

• piping or seepage,

• seismic liquefaction,

• structural, maintenance and unknown causes.

What could cause the failure ?

7/ The likely Causes

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• Video Show

• ********** Model Dam Fail - YouTube.mp4************

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Mount polly situation

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• Video show

First part

******The fallout from the Mount Polley mine spill in B.C. -

YouTube.mp4*******

What does the experts say ?

Cross-sections of the Mount polly dam showing the Evolution of the situation of the dam failling.

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• Residents downstream have been banned from using the water from river systems.

• The area of the spill is upstream of the Fraser River and is a major

spawning ground for salmon.

The Consequences

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8/ Consequences of this disaster

• Video show

Second Part

******The fallout from the Mount Polley mine spill in B.C. -

YouTube.mp4*******

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Conclusion • Mount Polley’s 235-hectare is primarily an Upstream

method designed dam (as we saw it before), the cheapest, weakest and most inappropriate sort of dam design for this geological setting.

• For more than three decades, professional engineers have condemned the use of this method due the sorry history of tailings breach failures the world over resulting from this inherently weak design, a fact which was well known by government and consulting engineers when this dam was approved in October 1992

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9/ conclusions

Advises for this kind of Project !

• Good maintenance programmes are, therefore, an essential requirement of effective tailings impoundment management, a vital component of which is a comprehensive surveillance programme (Martin and Davies, 2000).

• Structured settlement cracking and wet spots (line saturation) on the dam face are all good qualitative visual indications of potential problems.

• Piezometers, clinometers and pressure gauges may all be employed to good effect in a sensibly designed monitoring protocol (Vick, 1983; Vandeberg et al., 2011).

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10/Advises

Presentation sources 1. Independent Expert Engineering Investigation and Review Panel :

Report on Mount PolleyTailings Storage Facility Breach - January 30,

2015.

2. Journal of RIVERS WITHOUT BORDERS : Mount Polley Mine Report Shows

Inherent Risks of Watered Tailings Impoundments - Spring 2015.

3. Baseline data & initial impacts of the Mount Polley tailings pond

breach on adjacent aquatic ecosystems Ellen Petticrew, Nikolaus

Gantner, Sam Albers, and Phil Owens Quesnel River Research Center,

UNBC, 3333 University Way, Prince George, British Columbia, V2N 4Z9,

Canada.

4. CKPG NEWS and Glob Now_B.C Tv News (Videos from youtube).

11/ Presentation sources

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