Mining for Closure: Policies, practises and guidelines for sustainable mining and closure of mines

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. 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.

Self sustaining condition (no maintenance)

Developed sustainable condition (passive care or maintenance – rangeland, forestry, recreation ...)

Mine rehabilitation

Mine development & operation (active care and maintenance

After Robertson, Devenny & Shaw (1998)

Figure 4.2 Long term developed sustainable land use

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

Table 3 Land-use definitions (after Robertson et al (1998))

Term

Definition

Sustainable use

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.

Self 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.

Passive care sustainable use

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.

Active care sustainable use

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MINING FOR CLOSURE