66 / 120
48
MINING FOR CLOSURE
comparison, the following clarifications regarding
the difference between active and passive care from
van Zyl
et al
(2002a) is provided:
“the passive care programme is a period of moni-
toring and management designed to demonstrate
that the active care programme has been success-
ful and the ‘walk-away’ state has been achieved.
It must be noted that moving from the active care
stage to the passive care stage requires that there
is not ongoing mechanical water treatment on
the site, such as a lime treatment plant for acid
drainage. Similarly, moving from the active care
stage to walk-away may not be accomplished at
all at mine sites where passive treatment, water
monitoring, and ongoing maintenance are re-
quired”.
This also serves to underline the difficulties for a
miner to achieve traditional “closure” and walk-
away where ongoing environmental issues – par-
ticularly water issues – remain.
81
It should also be
noted that due to the relatively short history of site
rehabilitation (as such “mine closure”) it seems rea-
sonable to assume that even advanced jurisdictions
have much to learn – the true success of closures
will only emerge in the longer term.
In summary, it can be underlined that current regula-
tory requirements in developed mining nations often
favour or demand rehabilitation of mining or miner-
als processing sites to conditions approximate to pre-
mining conditions. As such, regulatory requirements
often aim for a return to self-sustaining eco-systems.
The point is made here however, and appears in
the literature surrounding this topic, that require-
ments to re-grade to
original
topography; to re-es-
tablish
only
indigenous rather than commercially
Figure 4.2
Long term developed sustainable land use
Developed
sustainable
condition
(passive care or
maintenance –
rangeland,
forestry,
recreation ...)
Mine
development
& operation
(active care and
maintenance
Mine
rehabilitation
Self sustaining
condition
(no maintenance)
After
Robertson,
Devenny &
Shaw (1998)
Table 3
Land-use definitions
(after Robertson
et al
(1998))
Term
Sustainable use
Self sustainable use
Passive care sustainable
use
Active care sustainable
use
Definition
Use or uses that can be sustained indefinitely with the resources provided (including fis-
cal resources), or which can be generated by the use. Renewable resource uses (forestry,
hydro development, commercial recreation, etc.) are typical examples. Uses that are sub-
sidised (e.g. from a trust fund) are examples of fiscally augmented but sustainable use.
Use that is sustained by natural processes and does not require anthropogenic interven-
tion. Examples include unmanaged wilderness or nature reserves with no maintenance.
Use that requires infrequent, periodic and low effort (anthropogenic input) in order to
maintain the sustainable condition or use. Examples include grazing rangeland where
passive care and maintenance is required.
Use that requires frequent or continuous high level effort (anthropogenic input) in order
to maintain the sustainable condition or use. Examples include the operation and main-
tenance of a water treatment plant for contaminated site discharges.
81. Where a mine has water quality issues, these typically continue
well past closure and can be very significant in cost particularly if
they require continuing treatment for decades after closure. This
typically applies to most sulphide ore bodies but in view of neutral
drainage this can apply to a larger group of mines. It should be
noted that financial assurance requirements must address long-
term care issues.