Mount Morgan Mine Upper Mundic Gully TSF EA Amendment

Table 3.2

Summary of considered failure scenarios

Initial water elevation (1)

Downstream weather condition Sunny day (no concurrent rainfall) Sunny day (no concurrent rainfall)

Scenario

Embankment

Failure mechanism

1

Stage 1

Piping

RL 295.6 m

2

Stage 3

Piping

RL 310.7 m

3 Sunny day (no concurrent rainfall) (1) The initial water elevation was defined as the operational level plus the 120-hour PMP storm volume containment for Stages 1 and 3, and at the spillway invert for Stage 5. Stage 5 Piping RL 328.5 m

Project No PS213278 Sandstone Gully TSF Dam Break and Consequence Category Assessments Mount Morgan Gold Mine Heritage Minerals

WSP January 2025 Page 13

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