Item
Stage 1
Stage 2
General economic loss or property damage
Low No dwellings, roads or any other third-party assets are expected to be harmed. However, it is expected that the discharged outflows cause minor impacts (less than $1 million in rehabilitation/compensation) to farm supply/use downstream. This category does not include the economic
Same as Stage 1.
(embankment, access roads, pits, etc.).
Overall consequence classification
Low
Low
6.4 Failure to contain (seepage) consequence
6.4.1 Population at risk
No PAR is expected for both embankment stages as there no ground water bores used for water supply in the vicinity of the TSF.
6.4.2 Potential loss of life
Similarly to PAR, no PLL is expected.
6.4.3 Environmental considerations WSP has recently completed a seepage management plan for Upper Mundic Gully TSF (WSP, 2026). The seepage management plan aims to present an initial characterisation of potential seepage behaviour based on the current understanding of the hydrogeological and geological conditions at the site. Based on the conceptualisation documented in the seepage management plan, the review suggests that seepage from the TSF may migrate into surrounding formations, with the potential for seepage pathway to the north-west of the TSF. Groundwater Dependent Ecosystems (GDE) data and groundwater borehole locations were retrieved from the GDE Atlas (Bureau of Meteorology, 2019) and Queensland Globe (Queensland Government, n.d.), respectively, for the vicinity of the Mt Morgan site. Figure 6.3 illustrates the local aquatic and terrestrial GDEs, as well as the water supply boreholes, against a 1 km and 10km radii from the proposed Upper Mundic Gully TSF. Although no water supply bores are within 1 km of the proposed TSF, low and moderate potential terrestrial GDEs are Based on the conceptualisation in the seepage management plan (WSP, 2026) and potential north-west seepage flow direction, the area identified as a low to moderate potential for GDEs may be impacted. Environmental impact therefore has been classified as significant due to this potential impact. It should be noted, however, that the presence of GDEs has not been confirmed through a physical survey. The assessment of impact is therefore based on the available information and our current understanding of seepage and downgradient receptors. It is recommended that further analysis and modelling is completed to refine seepage understanding, and to complete an ecological survey for the area north-west of the TSF to confirm the presence of GDEs.
Project No PS213278 Upper Mundic Gully TSF Stage 1 and 2 DBA and CCA Mount Morgan Gold Mine Heritage Minerals
WSP May 2026 Page 33
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