Mount Morgan Mine Upper Mundic Gully TSF EA Amendment

∕ Changes to Spillway are derived from Table 6 from the DETSI Manual for assessing consequence categories and hydraulic performance of structures; ∕ Changes to DSA are derived from Table 3 of ANCOLD requirements; ∕ Changes to mandatory reporting level are derived from Table 5 from the DETSI Manual for assessing consequence categories and hydraulic performance of structures; ∕ The updated CCA for Sandstone Gully TSF is provided in Appendix B.

Table 12. Proposed Table H3 Replacement

Name of Regulated Structure

Spillway

Design Storage Allowance

Mandatory Reporting Level

Sandstone Gully Tailings Storage Facility

1:20 AEP

Peak discharge from a 0.001 AEP storm of critical time of concentration on the total

1:10 AEP 72-hour ESS

1:100,000 AEP + Wave run- up allowance for 1:10 AEP wind

1:100 AEP 72-hour duration ESS

natural catchment with diversions inoperable

1:5 AEP Wet Season Water Storage DSA

2.3.3 Figures within the EA Justification for amendments to Schedule I, Figure 1 include: ∕ Inclusion of the Upper Mundic Gully TSF to ensure consistency with Table A1; and ∕ Inclusion of the pipe corridor to ensure consistency with Table A1. The proposed replacement Schedule 1, Figure 1 is provided in Figure 9.

Project number: 25B061

Page 33

Powered by