Open-cut coal mines

Activities that lead to disruption of, and changes to, natural surface drainage and runoff associated with open-cut coal mines in the Maranoa-Balonne-Condamine subregion are associated with nine of the 30 highest ranked hazards. These potential impacts occur because open-cut coal mines may potentially divert rivers and creeks, and divert the natural direction of rainfall-runoff by the construction, or expansion, of the pit and associated mine infrastructure and work areas, and by re-contouring landforms and discharges.

The potential impacts of leaching is associated with eight of the 30 highest ranked hazards, including leaching from:

  • in-pit waste rock dumps and backfill
  • waste rock dumps outside of the pit
  • coal stockpiles (in and out of the pit)
  • run-of-mine (ROM) plants
  • tailings decant water dams.

The following are identified as having the potential to link, or cause leakage between, aquifers:

  • incomplete or compromised cementing of groundwater supply and monitoring bores
  • mine expansion too close to a water body
  • abandoned exploration and appraisal bores.

These – together with deliberate pit wall dewatering, subsidence and enhanced aquifer interconnectivity caused by post-closure water filling the pit – are identified as potentially important hazards. The remaining 30 highest ranked hazards include:

  • soil erosion caused by heavy rainfall or failure to successfully rehabilitate abandoned mines
  • artificial groundwater recharge (following pit abandonment)
  • groundwater and surface water contamination via drill cutting disposal.

Figure 30 plots the 30 highest ranked hazards (and their associated activities and impact modes), ranked by midpoint of their hazard priority number. The figure shows the range of hazard scores and hazard priority numbers for each of these hazards.

Details of the hazard analysis are available at Bioregional Assessment Programme (Dataset 1).

Figure 30

Figure 30 Highest ranked hazards (and their associated activities and impact modes) for open-cut mines, ranked by midpoint of the hazard priority number

The x-axis shows the hazard priority number and hazard score for potential hazards. The intervals between the highest and lowest hazard priority number are shown in dark blue; the intervals for hazard score are shown in light blue. The same hazard may appear multiple times, as it may arise from a number of different life-cycle stages and activities. Hazards are listed with the syntax [Life‑cycle stage][Activity]:[Impact mode], where life-cycle stages are indicated by (E) for exploration and appraisal, (D) for development, (P) for production, (C) for closure and (R) for rehabilitation.

Typology and punctuation are consistent with the hazard analysis (Bioregional Assessment Programme, Dataset 1).

Data: Bioregional Assessment Programme (Dataset 1)

The hazard analysis also indicates the possibility of cumulative impacts associated with vegetation removal and diversion of site drainage lines around CSG plants, mines and pipeline corridors. Individually these hazards are not deemed to be relatively important, but they are in the top five ranked impact causes for activities associated with open-cut mines and CSG operations. These hazards are deliberate and associated with many activities, and are therefore likely to contribute to other stressors in the environment.

Last updated:
16 October 2018
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