WATER
A weep berm is a good example of applying the appropriate techniques to manage discharged water.
the form of more and larger water storage
facilities with adequate pumping capacity.
These interventions, of course, have
operational and cost implications for a
quarry, as every innovation usually requires
some level of capital expenditure or
equipment, as well as regular and ongoing
monitoring and maintenance.
30 _ QUARRY SA | JULY/AUGUST 2018
For instance, the aspect of applying for
and complying with a water use licence is
more and more onerous, requiring input
from specialised environmental scientists.
Geotechnical engineers work regularly with
water experts to ensure pit slope stability,
and civil engineers become involved in the
design and construction of attenuation
ponds, pumping facilities, pipelines, sumps,
and trenches.
Managing depth
Deepening of a quarry can also
complicate the storage design, as the
sump and storage area gets smaller at
the bottom of the pit as the excavation
increases in depth. Pumping capacity
must increase to avoid flooding, as water
needs to be transferred to reservoirs or
ponds at either intermediate level or
on surface.
Safety, too, becomes a factor when pits
deepen and the quarry highwalls become
steeper, as water pressure from behind the
wall can be a destabilising factor. Managing
this pressure is then a vital aspect of the
geotechnical considerations in maintaining
highwall integrity; vertical boreholes may
need to be drilled around the pit to extract
water before it reaches the highwall, and sub-
horizontal holes into the wall may also be
necessary to facilitate drainage into the pit.
From this cursory outline of some of
the factors that quarries will face today
when pursuing greater water efficiency, it is
clear why an integrated approach to water
management is increasingly necessary.
Hydrologists and hydrogeologists certainly
have a central role in applying their insights
to how water flow in quarries is understood,
managed, and utilised — but there are a range
of experts in other disciplines that need to
help quarry owners remain compliant and
water-wise.
The deeper a quarry becomes, the more critical it is to manage the
water effectively.