Mount Morgan Mine Upper Mundic Gully TSF EA Amendment

Aspect

Potential Impact

Risk Rating

Risk Controls

Residual Risk Rating

Treatment

L

C

R

L

C

R

groundwater receptors

Installation of liner in embankment to reduce potential for seepage Annual regular maintenance inspections in accordance with EA conditions in Schedule H and the Manual for Assessing Consequence

Regular seepage analysis of piezometers to be installed within TSF embankment Ongoing tailings sampling during tailings discharge to ascertain chemical parameters of material. Update existing groundwater model to include information from recently installed bores Adherence to Seepage management plan Update existing groundwater model An assessment of the physical and chemical properties of the tailings will be completed following cessation of tailings discharge to inform closure and capping strategies. Given lack of suitable material onsite to borrow, import strategy and amelioration methods will be developed towards end of TSF life.

Categories and Hydraulic Performance of Structures (ESR/2016/1933) .

The results of the geochemical modelling provided in Table 33 indicate that the final tailings solution analytes do not exceed any of the HILs and it is concluded that leaching from the tailings material is benign to human health Amendment does not propose any changes to rehabilitation strategies or objectives in a way that results in different impacts on environmental values or increases environmental harm than what is previously permitted under the EA. The land outcome to be achieved is a Non Use Management area to match that approved for other mine features in the EA. Amendment seeks to assign similar rehabilitation commitments that exist for the Sandstone Gully TSF to

Land

Inability to achieve a rehabilitated site that is safe, non polluting, stable and able to sustain an appropriate land use

Possible Moderate 13

Unlikely Moderate

9

the upper Mundic Gully TSF justified on the basis that the

Project number: 25B061

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