• PAR: Number of buildings or other places of occupation within the failure impact zone, or people
working or travelling through a potential impacted zone. Occupancy rate of the impacted areas,
duration, and frequency, considering itinerant and non-itinerant populations are used to
calculate the PAR; and
• PLL: Based on PAR and expected fatality rates, which are based on a combination of flow
depth and flow velocity.
The severity of loss and damage has been estimated using the maximum flood inundation and severity.
The overall severity is determined based on four categories:
Total infrastructure cost;
•
Impact on owner’s business;
•
Health and social impacts; and
•
Environmental impacts.
•
4.3.2.2.2.
DETSI Guidelines
The consequence category based on the DETSI Manual has been estimated in terms of the following
three failure types:
1) Failure to contain – Overtopping, spills or releases from the structure that result from loss of
containment due to overtopping of the structure.
2) Dam break, collapse of the structure due to any possible cause.
3) Failure to contain – Seepage, spills, or releases to ground and/or groundwater via seepage
from the floor and/or sides of the structure.
4.3.2.2.3.
Dam Break Consequence 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 20 presents the total PAR for each scenario, according to ANCOLD and Table 21 presents the
permanent and itinerant PAR for each scenario, according to DETSI. As noted in the CCA report, the
latter discounts mine personnel or persons located in an area with inundation depths lower than 0.3 m
from the estimates.
84
Wulguru Technical Services Pty Ltd – Supporting Information to Amend an Environmental Authority
Powered by FlippingBook