The results of the geochemical modelling provided in Table 29 indicate that the final tailings solution
analytes do no exceed any of the HILs and it is concluded that leaching from the tailings material is
benign to human health. When tailings are appropriately stored in a well maintained TSF subject to
regular inspections and monitoring, the tailings materials are generally considered benign to ecological
receptors. This proposed amendment provides commitments for the installation of a groundwater
monitoring array around the Upper Mundic Gully TSF to assess potential groundwater impacts.
Removal of contaminant sources from the environment is likely to reduce inflows into existing sumps
from groundwater and sub-surface flows in comparison to those under existing conditions. This is
expected to result in improved performance of the existing seepage interception system and reduction
in poor quality seepage expressing to the receiving environment i.e. Dee River. Disposal of tailings
generated through reprocessing is unavailable however the proposed Upper Mundic Gully location and
design reduces the likelihood of groundwater impact from occurring.
Based on the above, these proposed amendments are unlikely to result in further impacts to
groundwater values and Dee River downstream riverine systems. Overall, the recommencement of
operations at Mount Morgan is expected to result in the reduction of contaminant sources via the
reprocessing of mineralised tailings dams and remediation of operational areas, which will reduce the
existing volume of mine affected seepage. As a result, it is anticipated that groundwater quality will
improve during and post mining and that there will be no actual or potential adverse effect on
groundwater from the operation of the activity
6.3.3. Management Practices
The primary objective for groundwater management will be to minimise the release of mine affected
seepage from Project operational areas while progressive tailing reprocessing and Mount Morgan Mine
remediation occurs in accordance with the State’s Rehabilitation Plan (Unger et al, 2003) and Phase 2
Agreement. This will protect EVs and WQOs of receiving groundwaters from further degradation.
As with the existing Regulated Structures contained in the EA, the Upper Mundic Gully TSF will be
subjected to annual regular maintenance inspections in accordance with EA conditions in Schedule H
and the Manual for Assessing Consequence Categories and Hydraulic Performance of Structures
(ESR/2016/1933) . These inspections must be undertaken by a suitably qualified and experience
person.
In addition to these inspections, the Heritage Minerals Water Management Procedure provides
standard controls for various Project activities including tailings and water management, chemical and
hazardous material storage, and wastewater management in accordance with environmental best
practice and relevant guidelines and standards.
6.3.3.1. Groundwater Monitoring
The proposed amendment will not introduce any new contaminants of concern or increase current
observed concentrations of potential contaminants. Given the lack of groundwater monitoring bores
within the Upper Mundic Gully area, the installation of groundwater monitoring bores prior to
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Wulguru Technical Services Pty Ltd – Supporting Information to Amend an Environmental Authority
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