To assess the potential impact of Heritage Minerals Project to groundwater and the operation of the Upper Mundic Gully TSF, Table 41 provides a summary of expected outcomes for each catchment associated with groundwater flows. This builds on the post mining conceptual source- pathway-receptor summary anticipated changes to the hydrogeological system and modelled groundwater inflow changes developed by GHD (2017) and RGI (2010 and 2011) groundwater
catchment mapping and simulated groundwater flows. Table 41. Potential Scenarios for Groundwater/ Seepage Flows
Sub catchment
Heritage Minerals activities
Potential Scenarios
Arnolds Gully
Reactivation of Horse Paddock Waste Rock Dump
Improved surface water drainage reducing infiltration and subsequent poor-quality seepage via careful placement, compaction, shaping and capping of ARD waste rock by placement of overlying NAF waste rock. Potential for seepage water quality to further degrade in short term (reduced recharge), draining and expressing to Arnolds Sump. Likely reduced poor quality seepage to Arnolds sump in medium to long term (reduced recharge). Improved surface water drainage reducing infiltration and subsequent poor-quality seepage via careful placement, compaction, shaping and capping by placement of overlying NAF waste rock. Potential for seepage water quality to further degrade in short term (reduced recharge), draining and expressing to Nelsons sump. Likely reduced poor quality seepage volumes to Nelsons sump in medium to long term (reduced recharge). Improved surface water drainage reducing infiltration and subsequent poor-quality seepage via removal of ARD generating mine waste (tailings). Potential for seepage water quality to improve in short term (ARD source removal), draining and expressing to Nelsons Sump. Likely reduced poor-quality seepage volumes to Nelsons sump in medium to long term (reduced recharge). Improved surface water drainage reducing infiltration and subsequent poor-quality seepage via careful placement, compaction, shaping and capping by placement of overlying NAF waste rock. Potential for seepage water quality to further degrade in short term (reduced recharge), draining and expressing to 2 Mill sumps. Likely reduced poor-quality seepage volumes to 2 Mill sumps in medium to long term (reduced recharge). Improved surface water drainage reducing infiltration and subsequent poor-quality seepage via removal of ARD generating mine waste (tailings). Potential for seepage water quality to improve in short term (ARD source removal), draining and expressing to 2 Mill sumps.
Nelsons Gully
Reactivation of Horse Paddock Waste Rock Dump
Mining of 2 Mill tailings
No. 2 Mill
Reactivation of Horse Paddock Waste Rock Dump
Mining of 2 Mill tailings
Project number: 25B061
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