Identifying closure issues

Tommi Kauppila, Geological Survey of Finland, PO Box 1237, 70211 Kuopio, Finland; tommi.kauppila(at)gtk.fi

Defining closure objectives based on compilations of general closure objectives, analyses of risks and opportunities, and the requirements set by the post mining land uses form a good basis for identifying ‘closure issues’, i.e. the issues that in practice require actions to meet the closure objectives. There are several ways and tools to identify these issues to make sure that essential issues are not overlooked. The process also works in the other direction because identified closure issues can be used to set individual mine closure objectives.

Checklists

The most common method to identify closure issues is probably the use of checklists. For instance, this website can be seen as a collection of mainly technical closure issues (closure objectives are listed for Wastes and waste facilities, Water management, Water treatment, and Monitoring). Checklists used for mining project EIAs also will be useful in the closure context. An example of a generic checklist of mine closure issues is given below (adapted from Government of Western Australia 2011 and ICMM 2008):

  • Mine waste facilities
    • Geotechnical stability
    • Dusting
    • Seepage waters, water management
    • Reactivity, AMD generation; their prevention
    • Process chemical residues
    • Closure of the facility: cover structures, borrow materials etc.
  • Acidic, metalliferous mine drainage
  • Groundwater and surface water quality
  • Contaminated soils
  • Radioactivity
  • Fibrous minerals
  • Flora, fauna, habitats, biotopes, biodiversity
    • Rehabilitation, re-establishment of native vegetation
  • Geotechnical stability, subsidence
  • Built structures and facilities (decommissioning, recycling of materials, reuse)
    • Removal of equipment
  • Site safety (control of access)
  • Transport routes
  • Hazardous materials
  • Site water management; surface water flow patterns, structures
  • Post closure passive/low maintenance water treatment
  • Pit lakes, infilling, overflow
  • Resistance of structures to extreme climatic events
  • Visual impacts
  • Post closure monitoring; data management; maintenance
  • Regional economic effects
  • Effects on health, education, day care etc. facilities and activities
  • Demographic, employment, and work force effects (out migration effects)
  • Effects on housing and traffic

Spatial and functional domains

Another approach to screening for closure issues is to divide the mining concession and its surroundings to fairly homogenous spatial domains that contain similar processes, facilities or hazards and that may therefore require certain decommissioning and rehabilitation measures. This spatial model also can be extended beyond the immediate mining area where the division can be based on characteristics of the environment that receives the post mining residual emissions or other stressors from the closed mine. Examples of spatial domains useful for mine closure planning are given below:

  • Tailings management facility
  • Waste rock facilities
  • Ore stockpiles
  • Open pit
  • Underground workings
  • Haulage routes, access roads
  • Mineral processing facilities
  • Water treatment and management facilities, incl. passive systems and storage ponds
  • Workshops, fuelling, and maintenance
  • Power generation facilities
  • Pipelines, power lines etc.
  • Watersheds receiving waters from the closed mine (+aquifers)
  • Settlements
  • Important biotopes (wetlands etc.)

References

Government of Western Australia, Department of Mines and Petroleum & Environmental Protection Agency 2011. Guidelines for Preparing Mine Closure Plans. 78 p. http://www.dmp.wa.gov.au/documents/Mine_Closure%282%29.pdf

ICMM 2008. Planning for Integrated Mine Closure: Toolkit. International Council on Mining and Metals, London, UK. 84 p.