∕ Role of groundwater gradients and external sinks: Local groundwater gradients associated with the OCP (acting as a groundwater combined sink east of the TSF) and the inferred groundwater divide along the northeast-southwest trending topographic ridge are expected to control the direction of seepage migration, eastward toward the pit in areas hydraulically connected to it, and westward migration toward Turner Creek where seepage occurs on the opposite side of the divide. Tunnel Management Under current conditions, impacted water from the ephemeral dam has the potential to migrate through the tunnel and daylight into Dam 8, which is located off the mining tenure, and is not a mine feature included in the EA. It is acknowledged that a moderate rainfall event must occur to facilitate the flow event between the two areas. Water quality sampling results obtained from a sampling event undertaken during February 2026, using pH as the primary contaminants of concern, did not indicate that Dam 8 is impacted. 5.10 The stormwater tunnel inlet is within the TSF footprint is proposed to be plugged prior to embankment construction to mitigate potential deformation or collapse of the tunnel void beneath the embankment fill. The tunnel portal plug comprises a 1.5 m concrete plug located in competent rock approximately 5 m past the tunnel inlet which will then be backfilled to support the embankment. No mine spoil will be used in backfilling and sealing the tunnel. The concept engineering to support the tunnel plug is displayed in Figure 30 (refer to Appendix D for engineering drawings).
Project number: 25B061
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