Original EA Amendment

Figure 6.2

Fatality rate vs. DV for cases with little or no warning time

A fatality rate value of 0.01 has been adopted to account for uncertainties over areas where small DV values are reached for any values of DV below 30 ft 2 /s (2.8 m 2 /s) shown in Figure 6.2.

6.2.2.2

Results

The maximum DV product at the locations where PAR was estimated to be impacted presented values up to approximately 2.8 m 2 /s. Areas where DV presented values beyond this threshold were only identified within the drainage features and channel banks. A fatality rate of 1% was deemed suitable for the PLL estimation reflecting the relatively mild flood severity of the impacts from the hydraulic modelling (H4 and below for the PAR locations as discussed in Section 5.2.2). Table 6.6 and Table 6.7 presents the estimated PLL for each failure runout scenario, according to ANCOLD [2] and DETSI [3], respectively.

Table 6.6

PLL estimates according to ANCOLD

PLL

Stage 1

Stage 2

Mining operations

0

0.5

Township of Mt Morgan

0

0.1

Itinerant

0

0.0

Total

<0.1

0.6

Project No PS213278 Upper Mundic Gully TSF Stage 1 and 2 DBA and CCA Mount Morgan Gold Mine Heritage Minerals

WSP JUly 2025 Page 28

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