3.2
Alternatives to the Amendments
3.2.1 Amendment #1 Most land within the Mount Morgan Mine tenures are highly disturbed from historical mining and waste disposal activities that has resulted in source contaminants remaining in-situ and caused significant environmental harm to the receiving environment. There is a lack of suitable areas within the mining tenure to construct a new TSF due the presence of historically placed waste material, relatively limited undisturbed areas within the ML and diverse topography. A siting assessment was performed to inform TSF design and though this it was determined that the Upper Mundic Gully area provided the most favourable conditions to reduce long term stability risks, seal exposed historic waste rock dumps and accommodate the dimensions of the proposed TSF. An options assessment to determine potential locations for processed tailings disposal is provided in Table 16. The preferred option chosen to support this proposed amendment is highlighted . Table 16. Processed Tailings Disposal Options Assessment
Option
Advantages
Disadvantages
Do nothing
∕
Avoids further disturbance at a significantly modified and contaminated site
∕
Given the constraints in building Sandstone Gully TSF, this option does not provide a TSF and the remediation project can not continue Independent Technical Engineer unlikely to support mine plan Unavoidable impacts to some MSES however management strategies are proposed to reduce impacts Requires an amendment to the EA
∕
Discharge produced tailings into Upper Mundic Gully TSF
∕
Permanently stores processed tailings and allows Heritage Mineral’s rehabilitation project to continue
∕
∕ Majority of TSF footprint is a highly disturbed environment associated with previous mining activities ∕ Provides long term tailings management capacity given the conditions in Sandstone Gully footprint do not support establishing a TSF immediately. ∕ Favourable topography that provides for a valley TSF geometry that reduces stability risks ∕ Currently exposed waste rock dumps will be encapsulated by the TSF ∕ Upper Mundic Gully footprint is
∕
hydrogeological and topographically upgradient of existing environmental impacts at the Mount Morgan Mine Avoids sterilization of resources as treated tailings deposition will occur in an area with no known latent tailings resource recovery
∕
Discharge additional produced tailings into Sandstone Gully TSF
∕
Building the Sandstone Gully TSF is currently constrained due to the presence of more latent tailings than originally anticipated. These conditions
∕
Permanently stores processed tailings
Project number: 25B061
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