Figure 6.1
Mine personnel distribution
— Within the urban area of Mt Morgan, it was assumed that an average of two people per house affected by the flood extents are exposed during both day and night. These estimates were based on Census data presented by the Bureau of Statistics [24]. — No itinerant population along the roads was considered in the PAR calculations as the flood modelling results indicate minor impact to access networks and roads within the township of Mt Morgan. — No civilians are routinely expected within the mining lease; therefore, only mine personnel were considered in the impacted areas of the site. — No reductions in the PAR were considered for Upper Mundic Gully TSF due to limited warning/evacuation time assumed and the rapid progression of breach and outflow in the event of a failure, following ANCOLD [2] recommendations. This also accounts for the uncertainty associated with estimating the PAR and the expected rapid escalation of outflow to potentially occupied areas.
6.2.1.2
Results
For Scenario 1 (Stage 1), no mine personnel or Mt Morgan dwellings are expected to be impacted by the floodwaters, and the PAR was considered zero for both DETSI and ANCOLD methodologies. For Scenario 2 (Stage 2), mine personnel would be impacted at the process plant and the No. 2 Mill Tailings areas, yielding a total PAR of 45 for those locations, accounted for using the ANCOLD methodology. Additionally, four dwellings within the urban area of Mt Morgan were impacted for Stage 2 using the ANCOLD methodology, which yielded a PAR of 8. This number reduced to two dwellings for the DETSI methodology, where flood depths are required to be greater than 300 mm for there to be persons at risk. Table 6.4 presents the total PAR for each scenario, according to ANCOLD [2] and Table 6.5 presents the permanent and itinerant PAR for each scenario, according to DETSI [3]. As noted in Section 6.2.1, the latter discounts mine personnel or persons located in an area with inundation depths lower than 0.3 m from the estimates.
Project No PS213278 Upper Mundic Gully TSF Stage 1 and 2 DBA and CCA Mount Morgan Gold Mine Heritage Minerals
WSP JUly 2025 Page 26
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