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Abstract
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Several recent incidents concerning tailings dams at mines
have raised public concern about the safety of these structures,
and also about the environmental impacts during regular use.
As both UNEP and DHA have been called upon to evaluate the
extent of some recent disasters they commissioned a joint
survey with a view to:
- identifying common types of environmental and safety impacts,
- the actual frequency of such incidents,
-the environmental and human consequences of such incidents.
The survey was undertaken by the Mining Journal Research
Service. It was based on a database search, together with
a questionnaire to national authorities around the world.
The International Commission on Large Dams (ICOLD) also contributed
to the survey.
The survey collected details from over 52 separate incidents
in ... countries between 1980 and 1996. Five incidents involved
loss of life, the remainder causing primarily environmental
damage and property loss. Most incidents were associated with
some sort of failure in the dam wall, often triggered by violent
natural forces such as earthquakes or floods. However seepage
or discharge of effluent, hazardous dust, damage to habitats,
and poisoning of wildlife were also recorded.
The survey was unable to give an accurate picture of the extent
of the problem. It found that few countries collect systematic
statistics on tailings dam incidents, and there is no common
format for reporting. Many countries did not respond to the
questionnaire, and only the more dramatic incidents reported
in the international press were able to be identified there.
Finally, due to the strong preoccupation with safety issues
at dams, the true extent of environmental damage is probably
underestimated even in the reports that are available. Despite
these limitations, the survey provides a useful overview of
the situation in major mining countries.
The report suggests that much progress has been made in recent
years, but additional effort is needed by mining companies
and the authorities to minimize the risk of incidents. This
will be achieved through more widespread adoption of improved
design, construction and operational practices for tailings
impoundments, and the stipulation of safer practices through
legislation. Greater consideration should also be given to
the safety of adjacent communities in the case of sudden failure
of large tailings dams.
The report also indicates that a better system of collecting
and compiling statistics on tailings dam failures is required
before the true extent of the problem worldwide can be gauged.
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