Mine Closure - Mining and the Environment: From Ore to Metal - page 811

landforms in the vicinity. This may be quite a challenge, for example, if the project site is a
l at plain and the operations produce a deep pit and several large hills.
To support economically productive land uses, landforms need to provide the following:

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Accessibility - provision and maintenance of access to and access within the site;

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Usability - including factors such as all weather trafi cability, ease of cultivation;

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Physical stability against slope movement or erosion;

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Provision of soils suitable for establishment and survival of the proposed vegetation; and

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Potential productivity and economic yield

To support natural ecosystems, landforms need to provide:
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Physical stability;

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Surface relief, including micro-relief, to provide a range of habitat types to support a
wide range of l ora and fauna;

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Provision of soils suited for growth of natural vegetation; (soils suitable for establish-
ment of native vegetation may be more or less easily provided than soils suitable for
agriculture); and

●

Visual amenity.

For both types of land use, aspect can be very important, especially at higher latitudes.
Aspect, in this sense refers to the direction of a slope. It is an important but commonly
overlooked determinant of exposure to solar radiation and exposure to prevailing winds
which, in turn have a major effect on soil moisture. Landform design can be used in the
case of intended agricultural or forestry land use, to maximize formation of the most
favourable aspects. In the case of establishing natural ecosystems, the landform design
may be used to create a variety of different aspects, each of which will ultimately develop
different edaphic and habitat characteristics. Guidance in either case may be obtained by
observation of surrounding areas ( Case 21.2 ).
For surface mines, waste rock provides the most readily available medium for creation
of landforms. Placement of waste rock can be arranged to form the required shape, mini-
mizing the need for subsequent re-shaping. Of course, there may be constraints such as
acid rock drainage, which preclude certain shapes or arrangements of waste rock storages.
However, it is usually possible to create a i nal proi le that, when vegetated, will blend in
with the surrounding landscape. As discussed elsewhere, the creation of steep, 'angle-of-
repose' i nal dump slopes is inappropriate from several view-points, including stability,
practicability of rehabilitation and long-term accessibility.
Conventional tailings impoundments are less versatile in terms of landforms that can be
developed, as they unavoidably produce a large, l at to very gently sloping, concave crest.
Thus a drainage system needs to be installed to avoid periodic inundation. However, these
l at or gently concave surfaces may prove to be well suited to a variety of land uses ranging

The creation of steep, 'angle-
of-repose' fi nal dump slopes
is inappropriate from several
view-points, including stability,
practicability of rehabilitation and
long-term accessibility.

CASE 21.2
Limestone Mining in Northern India

In the limestone mining areas of the Lesser Himalayas in
India, trees are naturally restricted to the north-facing
slopes, the more exposed south-facing slopes supporting

only shrubs and grasses. Clearly, it is important that, if
forestry is the intended land use, landform design in this

situation should maximize the formation of slopes with a
northerly component.