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MODERN QUARRYING
July - August 2015
TECHNICAL FEATURE
SAFETY BERMS
M
any industr y lead-
ers and notably the
Department of Mineral
Resources (DMR) are
pushing for crest pro-
tection measures. Along haul roads and
especially inclined ramps, this is largely an
industry standard and widely accepted,
but there is a need to define safety berms.
• Safety berms are mostly used to
describe a continuous wall of loose
material emplaced close to a crest
edge to warn, discourage or prevent
pedestrians/vehicles from falling off
the crest edge.
• Haul road berms are safety berms that
are used along haul roads and espe-
cially inclined ramps. These berms are
often large and are generally long-
term or permanent installations.
• Rock traps or toe berms describe a
Bench crests
– the risks and remedies
Surface mines are becoming increasingly popular as a form of
mineral extraction around the world, partly as they are inherently
safer than underground mining methods, with a much reduced
rock-related risk. This does not mean that they are without risk. One
of the highest risk areas lies at the crest of production benches, where
persons/machines could fall off the edge or the weak crest could fail,
leading to potentially fatal consequences.
This paper by Applied Rock Engineering’s Dave Fenn looks at some of the risks associated
with crests and suggests actions to minimise them.
wall of loose material emplaced close
to the toe of a slope, primarily to pre-
vent rock rolling into the workplace
from the adjacent highwall (
Figure 1
).
They also act as a barricade and moni-
toring device, trapping fallen rock.
• Perimeter berms are placed around a
quarry to negate the effects of noise,
visual and dust pollution, and can
help to prevent inadvertent and non-
authorised access. These can be very
high and placed a safe distance from
the crest edge, anticipating post-clo-
sure instability.
There is little standardisation in the materi-
als tobe used in the construction. Examples
include waste overburden or aggregate
sand to boulders and are often a combi-
nation of material types and sizes. There
is also no standardisation in their con-
struction method required, compaction,
drainage and future maintenance. High
berms would have to be laid in lifts which
adds to the safety risk. The dimension of
safety berms is another area where many
standards have been adopted:
• They are often not constructed to a
particular standard of height or width,
being bigger where copious quanti-
ties of convenient waste materials of
various sizes exists.
• Guidelines in international literature
normally quote the berm height as
half the height of the largest TMM
wheel.
Consultant rock engineer Dave Fenn
(Photo: Dale Kelly).
Figure 1: Sandy rock trap designed to stop the rolling
rock threat from above and act as a barricade and even a
monitoring device, if rock is trapped.
Figure 2: Size of berm to halt a heavy truck.