Item
Stage 1
Stage 2
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 losses related to the owner’s business (embankment, access roads, pits, etc.).
Overall consequence
Low
Low
classification
4.3.2.2.9.
Failure to contain (Seepage) – Consequence
The Mount Morgan Mine Mundic Gully Stability Assessment developed by GHD provides information
about the hydrogeological behaviour near Mount Morgan mine. This study identified the following:
• Monitoring bore levels, along with storage data monitored from the OCP, provide and
understanding of the response of waste and tailings material to rainfall infiltration;
• Due to its upslope location, it is assumed that potential seepage flows from the proposed Upper
Mundic Gully TSF are directed towards the OCP;
• The preferential direction of groundwater flow from the OCP is suggested to be to east towards
Mundic Creek, as presented in the inferred groundwater contour map shown in Figure 42; and
• Seepage flows are expected to continue towards Mundic Creek, consistent with historical
observations. Therefore, seepage interception and management systems in place are expected
to be maintained.
Groundwater flow is in the direction of Dee River. It is expected that any potential seepage would be
directed to Dee River and be conveyed southwards along Dee River and not impact the area east of
Dee River.
Table 26 presents the “Failure to contain – Seepage” Consequence Category assessment according
to DETSI for both proposed embankment stages of Upper Mundic c Gully TSF according to DETSI.
Table 26. Consequence Category Assessment for Upper Mundic Gully TSF – ANCOLD (Environmental Spill)
Item
Stage 1
Stage 2
Low No loss of life is expected. The contamination of water supply bores is expected to affect the health of fewer than 10 people Low Seepage may reach area of low potential GDEs along Dee River, however impact is expected to be low based on elevation of creek bed and distance away. Additionally, low and
Same as Stage 1
Harm to humans
Same as Stage 1
General environmental harm
88
Wulguru Technical Services Pty Ltd – Supporting Information to Amend an Environmental Authority
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