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 the location of Upper Mundic Gully TSF by including it 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 Location 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. Although the Sandstone Gully TSF is approved as a mine feature in the EA, significantly more latent tailings are present within the footprint than was previously assumed. To enable the construction of Sandstone Gully TSF, removal of latent tailings must occur. However, due to the ground conditions, the methodology to remove latent tailings will be slower than allowed for in the original mine plan. Any delay to removing latent tailings from Sandstone Gully directly impacts construction timeframes for Sandstone Gully TSF. Upper Mundic Gully TSF 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). No transfer of water from the OCP to the Upper Mundic Gully TSF is proposed as part of this amendment. All references to an OCP-to-Upper Mundic Gully water transfer in the water balance report reflect a contingency scenario that was assessed for completeness of the risk assessment only and does not form part of the design or operational basis of the Upper Mundic Gully TSF. The water balance for the Upper Mundic Gully TSF has been assessed on the basis of no operational pond volume, with design storage sized to accommodate the Probable Maximum Precipitation (PMP) event without requiring an operational spillway. The OCP will continue to be managed independently in accordance with its existing approved water management framework. 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
Project number: 25B061
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