Approaches to Waste Rock Disposal - Mining and the Environment: From Ore to Metal - page 776

TABLE 19.3
Spacing between Erosion Control Treatments for Different Slope Angles

Slope Angle (º) Spacing - Slope Distance (m)

Up to 6 500

7 to 9 100

10 to 13 60

14 to 17 30

18 to 24 15

25 to 32 6

waste rock dumps, it is usually necessary to undertake frequent (at least daily in areas
of active dumping), detailed inspections for cracks that may be due to instability.
Unfortunately, it may be difficult to distinguish surface cracking due to settlement, from
cracking associated with developing slope failure. In some cases, instrumentation may be
used to identify and monitor slope deformations. This requires detailed geotechnical inves-
tigation and analysis. Surface cracks should be filled and covered, to prevent them becom-
ing internal conduits for rainfall runoff which could lead to or aggravate slope instability.
For waste rock storages constructed from the bottom up, inspections may be much less
frequent; weekly or even monthly inspections may be sufficient, except that additional
inspections should always be carried out following significant rainfall events. Inspections
are focused on identifying surface cracks, erosion gullies or damage to erosion control
measures, so that appropriate repairs can be carried out before major damage occurs.
Inspections should also check for signs of seepage or springs emanating from the face of
the storage, and if such occur, additional drainage and/or erosion control measures may
be required. Eventually additional monitoring programmes for acid drainage and for
rehabilitation may be required as discussed elsewhere in this topic.

For large top-down waste rock
dumps, it is usually necessary
to undertake frequent detailed
inspections for cracks.

REFERENCE

Lindbeck K and Hannan J (1998) Landform Design For Rehabilitation. Booklet in the
series Best Practice Environmental Management in Mining, produced by Environment
Australia, May, 1998.

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