Figure 4.3
Failure cone footprint - Upper Mundic Gully TSF Stage 2
The outflow volumes calculated for Stage 1 and Stage 2 embankments considers the total water volume ponded above the spoil dump crest. A summary of the total released volume in each scenario is presented in Table 4.2.
Table 4.2
Estimated outflow failure discharge for Upper Mundic Gully TSF
Parameter
Stage 1
Stage 2
Unit
Mm³ (1)
Total impounded volume
2.4
10.5
Failure cone volume
-
2.3
Mm³
Released ponded water volume
0.75
1.3
Mm³
Total outflow volume
0.75
3.6
Mm³
Total outflow
29
34
% of impounded
(1) Total impoundment volume includes deposited tailings and decant pond storing the 120-hr PMP event volume.
The estimated total release volumes for all scenarios presented in Table 4.2 have been validated against published research and studies on available historic tailings dam failures and release volumes. Historical release volumes presented in Rana et al. [16] and statistical models prepared by Larrauri & Lall [17] and Piciullo et al. [18] are plotted against the calculated released volumes in Figure 4.4.
Project No PS213278 Upper Mundic Gully TSF Stage 1 and 2 DBA and CCA Mount Morgan Gold Mine Heritage Minerals
WSP JUly 2025 Page 15
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