12 February 2020
20137096-009 Rev A
1.0 INTRODUCTION Heritage Minerals Pty Ltd (HML) has commissioned Golder Associates Pty Ltd (Golder) to assist with design studies for the storage of re-mined tailings at the defunct Mt Morgan mine. The scope comprises of undertaking the design of a single waste rock embankment across Sandstone Gully to contain the tailings. This study draws on the previous design work done previously by Golder for Carbine Resources Limited in 2015 2 , which had three embankments, each constructed using cycloned tailings.
Sketches for the concept level design were prepared and presented followed in our discussions on 15 th January 2021.
Further modifications to the concept design have been undertaken following our discussions, which are presented in this report, together with a Bill of Quantities.
2.0 BACKGROUND Peko and Anglo American dredged and retreated around 35 Mt of gold tailings from Sandstone Gully, with smaller tailings tonnages re-mined from at least three other tailings storage facilities (TSFs). Tailings is still left in all of these TSFs and Heritage Minerals plan to remine and retreat initial about 10 Mt of the remaining tailings.
3.0 DESIGN PARAMETERS AND CRITERIA
The layout of the proposed TSF and its embankment is shown in Figure 1 and drawings showing the concept embankment design are contained in APPENDIX A. Design codes and guidelines The most recent revisions of applicable design codes, regulations, and guidelines will be used in the detailed design of this TSF. These documents include, but are not necessarily limited to, the codes and guidelines listed below. 3.1
Australian National Committee on Large Dams (ANCOLD)
▪ Guidelines on Tailings Dams; Planning Design, Construction, Operation and Closure, 2012 and Addendum, 2019
▪ Guidelines on the Consequence Categories for Dams, 2012
▪ Guidelines for Design of Dams and Appurtenant Structures for Earthquake, 2019
Queensland guidelines
▪ High Hazard Dams with Hazardous Waste
▪ Assessing Consequence Hydraulic Performance.
2 Golder, Mt Morgan TSF, DFS, - 1540231-005, September 2016
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