Tailings Disposal - Mining and the Environment: From Ore to Metal - page 759

Monitoring

The impacts of DSTP are monitored using the following techniques:
●

Drop cores or grab samplers to provide samples of seabed sediment for laboratory
analysis;

●

Transmissometer probes to identify suspended sediment in the water column, often in
conjunction with STD proi ling;

●

Water sampling at various depths, and laboratory analysis;

●

Subsea visual observations using a Remotely Operated Vessel (ROV). Such observa-
tions are used to assess the condition of the DSTP pipeline, to observe the behaviour of
the tailings density current, and even to identify the behaviour of i sh in the vicinity of
the tailings plume;

●

Fishing surveys to assess species present and to enable tissue samples to be obtained for
laboratory analysis of metal concentrations.

While these monitoring procedures in water depths up to 200 m, can be undertaken at reg-
ular intervals similar to those that apply to monitoring of terrestrial systems, monitoring of
sediment deposition in very deep water requires highly specialized equipment and is very
expensive. The adopted approach is to undertake regular monitoring above a 200 m water
depth, at monthly or quarterly intervals to identify any unexpected occurrences and to
coni rm the absence of impacts on the important shallow water habitats. Monitoring of the
actual impacts of tailings deposition in very deep water is much less critical, and, because
of its high cost is generally carried out at intervals of two to i ve years.

Closure

Closure of DSTP systems requires little, if any, action. There is no compelling environ-
mental reason that the subsea pipeline needs to be retrieved, although potentially it may be
used on another project or for other applications. Onshore facilities require removal, and
would provide materials worth salvaging. Post-closure monitoring would logically involve
a deep water sediment sampling and analysis programme two years after closure, to assess
the extent of re-colonization. Should the results accord with previous studies which have
shown rapid re-colonization, no further monitoring would be required.

Closure of DSTP systems
requires little, if any, action.

REFERENCES

Aldous R (2002) Tailings Storage - Guidelines for Victoria (Discussion Paper), Department
of Natural Resources and Environment.
ATV-DVWK-M503 (2001): Grundlagen zur Überprüfung und Ertüchtigung von
Sedimentationsbecken. ISBN 3-935669-43-7.
Australian Government (2007) Tailings Management, Leading Practice Sustainable
Development Program of the Mining Industry, Department for Industry Tourism and
Resources.
Brehault H (1997) Tailings Management - A Placer Dome Perspective, Proceedings of
the International Workshop on Managing the Risk of Tailings Disposal, Sweden 1997,
International Council on Metals and the Environment (ICME).
BRGM (2001) Management of mining, quarrying and ore-processing waste in the European
Union, 79 p., 7 Figs., 17 Tables, 7 annexes, 1 CD-ROM (Collected data).