Geotechnical News December 2010
53
WASTE GEOTECHNICS
third of the failures occur in small to
intermediate size facilities: the released
tailings from such failures can be man-
aged relatively easily because of their
smaller amounts. The relative increase
in impact on public health and loss of
life should be associated with the fail-
ure of large dams.
Summary and Conclusions
This article aimed at understanding
the tailings failure history using
a statistical approach. Whereas a
significant portion of failure incidents
fell under the “unknown” category,
some general trends were developed
with respect to time and space, causes,
and consequences. The main findings
of this work can be summarized as
follows:
1. Tailings dam failures peaked to
around 50 events/decade in 1960s
through 1980s but have dropped
down to about 20 events/decade
over the last twenty years. The
frequency of such incidents has re-
cently shifted geographically from
developed countries to developing
countries.
2. The main reasons for dam failures
are “unusual rain” and “poor man-
agement” and these causes have a
profound effect on failure mecha-
nisms. The inclusion of climate
change effects in the initial design
and of the observational method
during construction, maintenance,
and monitoring are highly desir-
able.
3. Failures predominantly occur in
“small to medium” size dams that
are up to 30 m high and contain a
maximum tailings volume of 5 x
10
6
m
3
. Such incidents can be mini-
mized by employing proper engi-
neering standards and by avoiding
upstream construction as much as
possible.
4. Upon dam breakage, the released
tailings generally amount to about
one-fifth of those contained within
the facilities. Environmental pol-
lution and infrastructure damage
can be managed in “intermediate
failures”. Loss of life and health is-
sues are associated with large cata-
strophic spills.
References
ICOLD (2001).
Tailings Dams - Risk of
Dangerous Occurrences, Lessons
Learnt from Practical Experiences
,
Bulletin 121.
Peck RB. (1969). Advantages and limi-
tations of the observational method
in applied soil mechanics.
Geo-
technique
, 19(1):171-187.
Rico M, Benito G, Salgueiro AR, Diez-
herrero A, and Pereira HG. (2007).
Reported Tailings Dam Failures: A
Review of the European Incidents
in the Worldwide Context
. Elsevier,
Netherlands.
Vick SG. (1990).
Planning, Design,
and Analysis of Tailings Dams
. Bi-
Tech Publishers Limited, Canada.
Epilogue
The recent dam failure in Hungary
(October 4, 2010) that released about
700,000 m
3
of tailings and has a huge
impact on life, property, health, and
the environment, is a grim reminder of
the importance of understanding these
incidents more closely.
Shahid Azam, Ph.D., P.Eng.
Associate Professor
Environmental Systems Engineering,
University of Regina
Regina, SK, Canada, S4S 0A2
Tel: 1-306-337-2369
Fax: 1-306-585-4855
email:
Qiren Li, B.A.Sc., EIT
Environmental Engineer
Clifton Associates Ltd.
Regina, SK, Canada, S4N 5Y5
Tel: 1-306-721-7611
Fax: 1-306-721-8128
email:
Figure 6. Contaminant release during failure.
Figure 7. Socio-economic impact of failure.
