6.3.4
Consequence classification
6.3.4.1
ANCOLD
Table 6.10 presents the consequence category assessment for Upper Mundic Gully according to ANCOLD for the “Environmental spill” scenario of both embankment stages.
Table 6.10
Consequence Category Assessment for Upper Mundic Gully TSF– ANCOLD (Environmental spill)
Item
Stage 1
Stage 2
Minor
Minimal repairs are expected since there is no risk of a dam break. The repairs are more related to correcting erosion and addressing minor issues in the embankment.
Total infrastructure costs
Same as Stage 1
Minor
Impact on dam owner’s business
Same as Stage 1
Some restrictions.
Minor
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.
Health and social impacts
Same as Stage 1
Minor
It is expected that the spills from TSF will discharge in the Open pit and will be contained in Dee River banks when spills from the Open pit.
Environmental impacts
Same as Stage 1
Overall consequence classification
Low
Low
6.3.4.2
DETSI
Table 6.11 presents the consequence category assessment for Upper Mundic Gully according to DETSI for the “Failure to Contain – Overtopping” Scenario of both embankment stages.
Table 6.11
Consequence Category Assessment for Upper Mundic Gully TSF– DETSI (Failure to Contain – Overtopping)
Item
Stage 1
Stage 2
Low
No loss of life is expected. No contamination of water used for human consumption.
Harm to humans
Same as Stage 1.
Project No PS213278 Upper Mundic Gully TSF Stage 1 and 2 DBA and CCA Mount Morgan Gold Mine Heritage Minerals
WSP JUly 2025 Page 32
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