SECTION 7 Northern Rock Stack C:\D Data\GWS C Drive\GWS\Client Files\1344 OGL - WKP\4 Deliverables\WUG Effects Summary\June 2022\WNP Groundwater Effects Summary_Final_Rev_0.docx 26 7. Northern Rock Stack 7.1 Description The Northern Rock Stack (NRS) is an expansion of the existing northern stockpile area into the workshop area to the west, and farmland in the north as shown in Figure 28. The rock will be placed to a maximum elevation of 1,173 mRL. This will comprise a 76 m high engineered landform over a footprint of approximately 26 ha, containing up to 7.0 Mm3 of rock. Some rock will subsequently be used to backfill Gladstone and other underground mining stopes, reducing the maximum elevation of the stack. At closure, the NRS will have a capping layer that will have a maximum elevation of 1,148 mRL. The NRS will be constructed with an earth liner and drainage system that will collect the majority of the leachate it generates. Figure 28 Proposed NRS Layout 7.2 Characterisation The NRS site has been characterised by previously exploration drilling, operational investigation and monitoring, with some further investigations undertaken by EGL as shown on Figure 29.
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