5.6.1. Groundwater Quality
During 2024, GHD completed a review of groundwater quality data obtained from monthly groundwater
monitoring and to prepare a report to comply with EA conditions W7, W8 and W9. A copy of this report
is provided as Appendix I.
The monitoring network comprised of seven EA-listed groundwater monitoring locations (MB2, MB5-D,
MB5-S, MB7-D, MB8-D, MB9, and MB14) and an additional two bores (MB4-D and MB11). Heritage
Minerals provided groundwater monitoring data collected from August 2022 to September 2024.
Tabulated groundwater quality results are too lengthy to replicate in this report but are provided in
Appendix I. A description of the groundwater quality is as follows. Groundwater at the site is heavily
impacted with acidic conditions resulting in the mobilisation of metal species. Heritage Minerals have
not commenced operations at the site and groundwater impacts are due to legacy contamination. An
evaluation of the groundwater chemistry compared to groundwater quality guidelines identified multiple
exceedances and based on the statistical analysis, identified trends for selected analytes in certain
monitoring locations. The main outcomes of this assessment included:
• Exceedances of toxicant and physicochemical indicators were observed at all monitoring bore
locations;
• Metal concentrations exceeded the published water quality guidelines for all metal species. The
most notable exceedances were:
o Aluminium, with the maximum recorded concentration (3,590 mg/L) exceeding the
default guideline value (0.055 mg/L) by a factor of 65,000;
o Cadmium, with the maximum recorded concentration (0.605 mg/L) exceeding the
default guideline value (0.0002 mg/L) by a factor of 3,000;
o Cobalt, with the maximum recorded concentration (12.3 mg/L) exceeding the default
guideline value (0.001 mg/L) by a factor of 12,000;
o Copper, with the maximum recorded concentration (330 mg/L) exceeding the default
guideline value (0.0014 mg/L) by a factor of 236,000;
o Zinc, with the maximum recorded concentration (98.2 mg/L) exceeding the default
guideline value (0.008 mg/L) by a factor of 12,000; and
• Groundwater at most of the monitoring locations (all except MB9 and MB8-D) was found to be
acidic, with pH values ranging from 2.2 to 4.5.
5.6.2. Conceptual Site Model
As committed to through proposed amendments described in Table 5, groundwater monitoring bores
are proposed to installed in the periphery of the proposed Upper Mundic Gully TSF.
Most monitoring bores installed to date are located between sources of contamination and receiving
environment being the Dee River. Installation of groundwater monitoring bores in hydrogeological and
topographical upgradient locations has not been warranted by either the State or various EA holders.
Groundwater properties specifically within the Upper Mundic Gully TSF area have not been previously
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Wulguru Technical Services Pty Ltd – Supporting Information to Amend an Environmental Authority
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