Mining and Sustainable Development II - DTIE

Mining
have also been present in other tailings accidents,
the experience at Baia Mare has led to a number of
organisations, including UNEP, undertaking initiatives
aimed at preventing, or at least lessening,
the impact of such events as may occur in the
future. UNEP is working with various partner
organisations on key areas which are expected to
make a difference in the future.
Code for cyanide management in the gold
industry
The gold industry has signalled its intention to
develop a voluntary global Code for the management
of cyanide in mining. UNEP, working with
the International Council on Metals and the Environment,
is supporting this initiative. The two
organisations convened a multistakeholder workshop
in Paris in May 2000. Discussion commenced
at that workshop on issues relating to
scope, coverage and content, and a process was
agreed to oversee the work. A broad stakeholder
Steering Committee was established and there is
widespread consultation occurring within the gold
industry. There is strong support for such a Code
and it is expected to be implemented in early 2002.
Emergency preparedness and disaster
response
Adequate local awareness and preparedness for
emergencies is necessary to ensure that the critical
first response to an accident is rapid and effective.
In the past, community consultation for integrated
emergency response planning has not always
occurred at mining and minerals processing operations.
As one of the Baia Mare follow-up activities,
UNEP and the International Council on
Metals and the Environment held a joint workshop
on Emergency Preparedness and Disaster
Response in May 2000. Awareness & Preparedness
for Emergencies at the Local Level – the
APELL programme, provides a well established
general methodology which UNEP is now tailoring
to the specific characteristics and needs of the
mining industry and its communities. A handbook
for mining and minerals processing now
being developed by UNEP will be reviewed and
field tested with governments and companies during
2001.
Improving the effectiveness of regulation for
accident prevention in mining
As regulators of the mining industry, it is incumbent
on governments to examine the effectiveness
of their approach to permitting and monitoring
of those activities in mining, which, were they to
fail, could have large environmental and community
impacts. To assist in this process, the Australian
Government and UNEP co-hosted an
international workshop of regulators in October
2000. Government officials from some 25 mining
countries reviewed emerging practices in regulation
with a focus on the permitting of tailings
facilities and the use of chemicals such as cyanide.
Reviewing the lessons learnt from past mining
accidents and comparing actions taken by governments
to prevent their recurrence, it was
acknowledged that national and international
efforts on building appropriate skills to enhance
◆◆◆◆◆
regulatory capacity and learning to identify early
warning signs of impending accidents is needed
to improve the effectiveness of regulation for accident
prevention in mining.
Contingency engineering or “fail-safe”
features for tailings storage facilities
If sound principles and practices are followed in
the design, construction and operation of tailings
facilities, there should be few accidents in the mining
industry and hence little need to consider “failsafe”
or “back-up” features in the design and
location of dams. However, the frequency of
occurrences and potential consequences of dam
failures indicate the need for thorough consideration
of the potential which may exist for additional
safety features to be integrated into the
design of tailings facilities in order to minimise the
impact of a dam accident. Working with experts
on this issue, UNEP is calling together a targeted
group of people to examine the range of available
options, their benefits and costs, limitations and
applicability.
Notes
1 The full text of the Report, Cyanide Spill at Baia
Mare, UNEP/OCHA Assessment Mission
Report, April 2000 is available at www.naturalresources.org/environment/BaiaMare
2 Information on UNEP activities is publicly available
on the Mineral Resources Forum website at:
www.natural-resources.org/environment
◆
Tailings accidents and
lessons learned
“Tailings Dams: Risk of Dangerous Occurrences:
Lessons Learned from Practical Experiences” is the
title of a Bulletin to be released by the International
Commission on Large Dams (ICOLD) and
UNEP. The “practical experience” is presented in
the form of a review of some 230 tailings dam
accidents over the past 50 years, together with
examples of effective remedial measures. The Bulletin
aims to highlight some of the dam failures
commonly encountered so as to avoid similar difficulties
in future as these failures have been costly
to both life and the environment.
The Foreword to the Bulletin describes the
challenge:
“The disposal of wastes in our overcrowded world has
become a serious problem. Due to the nature of mining
and mineral processing, the volumes of mining
wastes are significantly larger than those of both
domestic and industrial wastes. The chemical characteristics
of the waste (particularly mobility of metal
constituents) are often of concern. The volumes of
mine wastes greatly exceed the total volumes of materials
handled by civil engineering throughout the
world. The crushed rock passed through the processing
plant to extract the desired product is discharged
from the “tail end” of the plant as the waste tailings,
and in many parts of the world forms the greatest volume
of mine waste, although at open-pit mining operations
the volume of waste rock may exceed the volume
of tailings. The fine particulate tailings are commonly
stored in impoundments retained by tailings dams.
The material is placed hydraulically and so is loose
and nearly saturated. Any major movement of the
retaining walls of the impoundment can induce
shearing strains that disturb the structure of the tailings
mass, inducing a rapid rise of pore water pressures
and liquefaction of a section of the impoundment,
causing even greater pressures to be applied to the
retaining walls. Failure of the retaining dam can
release liquefied tailings that can travel for great distances.
Water will flow through and around buildings,
but liquefied tailings, due to their greater weight
can destroy the structures. The increasing size of modern
mines means that tailing dams are becoming ever
higher and impoundments even larger.
Similarities between tailings dams and embankment
dams designed to retain water, have enabled
many of the design techniques used with embankment
dams to be applied to produce safe tailings dams, but
66 ◆ UNEP Industry and Environment – Special issue 2000