June 2022 G-14642.71-006-R-Rev0_FINAL 41 considered as an industry-standard practice. The stability of the end stope faces should also be evaluated as design progresses. 3) The following assessments that are not available in the current geotechnical assessment will be required as a part of the next design stages: a. Ground support regime. b. Vertical opening stability. c. Strength of the stope backfill options including cemented rock fill. d. Proposed geotechnical monitoring instrumentation during mining. WSP suggests the following approach be undertaken as part of the future geotechnical assessment: The geotechnical domains should be divided into the following two categories based on geotechnical logged data: o Specific information for empirical stope design calculations, in this case, the domains are divided into hanging wall and footwall (with a 20 m offset from the stope) and Ore Backs-Ends (vein). o A separate category, based on the interpreted lithology units, adjacent to the proposed WUG deposit (stope and underground mining infrastructure) for the mine scale numerical modelling. Composite the logged information into 1 m intervals to calculate the statistical parameters and their distribution for each geotechnical domain. Re-visit the structural information to estimate the likelihood of additional structural sets due to bias from the borehole orientation. The Map3D numerical modelling (elastic numerical analysis) uses the Factor of Safety (FoS) criteria to indicate the high-stress concentration and potential future instability, due to mine induced stress to the pillar, main underground infrastructures, and final crown stability (approximately 100 m below the surface). WSP suggests: o Carry out sensitivity analysis due to considerable variation of the available rockmass parameters and the assumed In-Situ stress regime. o Consider applying the ubiquitous joint model for the condition of the main structure sets.
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