|
“There are two main elements in the design of the dams
which store residue from mining operations - their
safety and efficiency, and their environmental
friendliness,” says Waldo Dressel of specialist
engineers Environmental Civil & Mining Projects (ECMP).
“This applies both when they are in use and after they
are closed.”
One of ECMP’s three divisions is dedicated to the
design of mine waste disposal facilities – a catch-all
description for reservoirs and dams used to store
residue and waste from mining operations. ECMP’s
professional signature can be found on a number of
such facilities in West Africa and in neighbouring
countries such as Zambia, Zimbabwe, Botswana and
Namibia, as well as South Africa itself.
In the design and 3D modelling of the dams and stacks,
Dressel uses an interactive software engineering
design software called Civil Designer, specifically
its Roads and Terrain modules.
Civil Designer is used through the entire design life
of a waste disposal facility – from the selection of
the site, to its final taking shape - and again at its
closure when its working life is done and it hopefully
blends back into the landscape.
“With Civil Designer, I am able to model each and
every stage in the dam design – its capacity, size and
shape. For example, is it to be square, or in a
valley? ” Dressel explains. “The Terrain module is
most useful in designing the terraces of the dam’s
inner and outer structure. I use it to create
cross-sections of the dam to arrive at volume figures
at each stage of the elevation. It also allows me to
measure deposition rates, the height of the dam walls,
and a capacity analysis which is based on |
the shape of the dam and the local topography. It’s
also very competent at helping me measure quantities –
for example, cut-and-fill volumes. “
One of Civil Designer’s most remarkable features is
its flexibility, Dressel says. “It’s exceptionally
user-friendly. I frequently customize it to get the
answers I need during the design of a dam, which can
be 20m to 30m high.”
So flexible is Civil Designer that Dressel sometimes
uses its Roads module to design the top surface of a
dam, where the top of the dam wall becomes the road.
In fact, the design problem is really identical. The
difference is the slope of the dam walls, which
Dressel designs, this time using the Terrain module.
The same software – developed by software house
Knowledge Base – is also used in the design of runoff
trenches, stormwater/return water dams, seepage and
underground drainage systems, and outfall pipes
associated with the main storage dam. Depending on the
nature of the waste, a single mine can have one or a
number of separate “mini-dams” or waste storage
facilities.
ECMP works closely with environmental authorities in
the design and closure of waste sites, and in the end
they have to be satisfied.
“It is essential to ensure that when a mine waste
disposal site is closed, all environmental and safety
requirements are met – that it is environmentally
secure and aesthetically acceptable,” Dressel says.
“This is yet another area where Civil Designer ‘s
great flexibility is again demonstrated.” |
