Table 6.4
PAR estimates (ANCOLD)
PAR
Stage 1
Stage2
Mining operations
0
45
8 (1)
Township of Mt Morgan
0
Total
<1
53
(1) PAR corresponds to four properties identified within flood extents
Table 6.5
PAR estimates (DETSI)
PAR
Stage 1
Stage 2
Mining operations
0
0
4 (1)
Township of Mt Morgan
0
Total
<1
4
(1) PAR corresponds to only two properties within flood extents impacted by flood depths greater than 300mm
6.2.2
Potential Loss of Life
The ANCOLD Guidelines on Risk Assessment [25] recommends the adoption of the Reclamation Consequence Estimation Methodology (RCEM), developed by the U.S. Bureau of Reclamation (USBR) [26], considering it the most suitable for applying to large dams in Australia based on the extensive database, guidance documentation and the industry experience in its application.
6.2.2.1
RCEM approach
The RCEM approach is based on empirical interpretation of dam failure and flood case histories from 1903 to 2013. The method relies on the accurate development of PAR values and the assessment of key factors such as: time to arrival (or warning time), time to flood peak, and the product of peak flood depth and peak velocity (also referred to flood severity). A series of curves have been fitted to case histories that relate the DV product to a fatality rate – in terms of the percentage of the PAR with little or no warning, partial warning, and adequate warning. The fatality rate estimation developed by USBR [26] was based on 80 case history data points for water floods. The warning time for all breach locations has conservatively been assumed as little to none. The USBR [26] upper suggested limit curve (considering little to no warning) shown in Figure 6.2 with a maximum fatality rate of 75% PAR has been adopted for this study.
Project No PS213278 Upper Mundic Gully TSF Stage 1 and 2 DBA and CCA Mount Morgan Gold Mine Heritage Minerals
WSP JUly 2025 Page 27
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