2. Overview of Proposed EA Amendments
Applications to amend an EA must be made in accordance with s.224 and s.225 of the EP Act and meet
the application requirements detailed in s.226. An application must also comply with s.226AA, s.226A,
s.226B, s.227 and s.227AA to be considered ‘properly made’. The proposed amendments within this
application intend to:
• Authorise Upper Mundic Gully TSF by inclusion as a mine feature in the EA;
• Update Table A1, and associated Schedule I Figure 1, to address to be determined (TBDs)
associated with the pipe corridor and exploration mine features; and
• Fix minor erroneous issues in the EA that impact on the processed tailings volumes for
discharge into Sandstone Gully TSF.
2.1. Proposed Amendments
2.1.1. Proposed Amendment 1: Authorise Upper Mundic Gully TSF
EA EPML00433013 currently authorises the disposal of processed tailings into the following locations:
• Up to 11.5 million cubic meters (Mm 3 ) into Sandstone Gully TSF; and
• Up to six million dry weight tonnes (6Mt) into Open Cut Pit (OCP).
This EA amendment application seeks to authorise a new disturbance area to provide additional tailings
storage in a facility known as Upper Mundic Gully TSF. In consultation with the Independent Technical
Engineer (ITE) for the Heritage Minerals tailings reprocessing project, engaged on behalf of the
Northern Australia Infrastructure Fund (NAIF), approval and operation of the Mundic Gully TSF is
desirable to further future proof the site wide tailings/water balance capacity and further reduce the risk
of environmental impacts uncontrollable releases. The ITE and other project stakeholders have used
the precautionary principle when determining an appropriate site wide tailings/water management
strategy which accommodates climate extremes. During January 2013, ex-cyclone Oswald caused
unusually intense rainfall over the Mount Morgan Mine that resulted in the first-ever overtopping of the
OCP. This event resulted in further environmental harm to the receiving environment as low pH water
from the OCP discharged directly into the Dee River. The ITE and other project stakeholders, including
the DNRMMRRD, as landholder and administrator of the AMLP, are committed to de-risking the
project’s tailings and water management strategy to reduce the likelihood of loss of containment
occurrences repeating.
An updated water balance model has been developed to understand the impact of the proposed Upper
Mundic Gully TSF on the water levels in the OCP and to confirm the level of spill risk from the OCP, if
any. The report is provided in Appendix G. Prior to Upper Mundic Gully becoming the TSF for the site,
it is not proposed to function as a water retaining structure. It will, however, during the construction
phase, naturally retain contributing catchment runoff once the tunnel has been closed off. It is not
intended to receive any other form of water from the site during the construction phase (i.e. prior to it
becoming the TSF). However, in spite of the intentions outlined above, the Upper Mundic Gully TSF
25
Wulguru Technical Services Pty Ltd – Supporting Information Report
Powered by FlippingBook