investigated, however groundwater properties of the Mundic Creek have. Accounting for some natural
variability and acknowledge the modified landform through previous mining activities, reliance on
Mundic Creek groundwater characterisation is considered an appropriate representation of the Upper
Mundic Gully hydrogeology.
Heritage Minerals Project will ultimately result in improved environmental outcomes at the Mount
Morgan Mine through the excavation and placement of historical ARD generating mine waste and
redeposition into purpose built TSFs, including Upper Mundic Gully TSF. This will result in the removal
of the source of ARD generating material from across the site and consolidation where modern capping
and closure solutions can be employed reducing recharge of and seepage from mine waste structures.
This will reduce impacts from the Mount Morgan Mine to the receiving environment including the Dee
River in accordance with the State’s Rehabilitation Plan (Unger et al, 2003) and Phase 2 Agreement.
A conceptual site model (CSM) has been developed to describe potential migration pathways between
the Upper Mundic Gully area and primary receiving environments being groundwater and the Dee River
and is displayed in Figure 44. The CSM has been developed to scale to highlight the topographical
reaches of the Upper Mundic Gully area and visualise how topography drives groundwater migration in
a south east direction towards the Dee River. When describing the CSM in this section, consideration
is given to all catchments and mine features within the mining lease and not just the Upper Mundic
Gully TSF footprint as the purpose of the CSM is primarily to conceptualise how groundwater can
migrate to environmental receptors.
The hydraulic gradients and inferred groundwater flow contours correlate well with pre-mining
topography (GHD, 2017). Overall, the interpreted groundwater flow direction is towards the southeast
and the Dee River and is not anticipated to change significantly due to seasonal variations in
groundwater levels (GHD, 2017).
Based on the geological conditions and soil properties of the Upper Mundic Gully area, the underlying
geological units include colluvium/alluvium, saprolite underlain by fractured bedrock and bedrock. GHD
(2017) provided a detailed summary of groundwater flows at the Mount Morgan Mine following review
of previous RGI (2003, 2005, 2010 and 2011) groundwater reports.
Mine affected water created from seepage or surface runoff is currently accumulated in numerous
facilities including Shepherds Holding, No 2 Mill, Frog Hollow and Mundic West structures. Once
collected, the seepage and/or surface runoff is either left to evaporate or pumped back into the OCP,
with this location being the primary storage location for contaminated water. Most seepage currently
reports to either the seepage sumps and subsequently the Sandstone Gully TSF and the OCP. This
water treatment system is owned and managed by the DNRMMRRD.
Existing seepage from the mine waste / tailings areas, inclusive of the Mundic Creek area and main
discharge points for subsurface and groundwater flow is summarised as a source-pathway-receptor
model in Table 33. Groundwater and sub-surface flows to for each catchment including to sumps and
receiving environment simulated by RGI (2011) are presented in Table 34. Simulated groundwater flow
per catchment is provided in Table 35.
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Wulguru Technical Services Pty Ltd – Supporting Information to Amend an Environmental Authority
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