provides additional capacity in a potential worst case scenario, should the OCP be at risk where it could
potentially overtop. The water balance has been undertaken to consider the scenario where OCP water
could be transferred to Upper Mundic Gully TSF across a range of probability percentiles.
The proposed location of the Upper Mundic Gully TSF is displayed in Figure 4. The Upper Mundic Gully
portion of the Mount Morgan Mine site is a highly disturbed environment that no longer free drains due
to the historical placement of waste rock material and operation of a human made tunnel that diverts
water from an ephemeral dam to Dam 8. Consequently, the hydrological regime of the Upper Mundic
Gully area has been significantly altered due to the placement of waste rock and the artificially created
OCP. The modifications to the Upper Mundic Gully landscape are described further in Section 4.1 of
this report.
The waste rock dump, referred to as the ‘Western Dump’ (this feature is not listed in Table A1 of the
EA) occupies a significant portion of the Upper Mundic Gully valley. There is no evidence that
rehabilitation methods have been applied to this feature (refer to image provided in Figure 14) and it is
likely that the Western Dump is contributing Acid Rock Drainage (ARD) seepage into the environment.
The Upper Mundic Gully TSF is proposed to tie into portions of the Western Dump to the extent
practicable, ultimately sealing the currently exposed rock face, further reducing potential ARD seepage
into the surrounding environment.
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Wulguru Technical Services Pty Ltd – Supporting Information Report
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