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DETSI Comment
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activities, reliance on Mundic Creek groundwater characterisation is considered an appropriate representation of the Upper Mundic Gully hydrogeology. 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. As discussed at the prelodgment meeting, providing an understanding of the conceptual site model is considered an appropriate way to demonstrate expected groundwater conditions within Upper Mundic Gully and satisfy 226A(1)(f) and relevant decision making criteria. A new Section 5.6.2 has been included to describe the conceptual site model. Purpose of this proposed condition is to improve on the existing conditions for Sandstone Gully TSF. Piezometers are proposed to be installed within the embankment to monitor the phreatic surface and detect potential seepage/ discharge of contaminants. The locations of the piezometers are to be finalised during the next design phase. The proposed condition within Table 7 has been revised to now state: • Permanent storage of tailings. • Construction of tailings embankment • Monitoring of seepage within embankment through installation of piezometers Figure 40 has been updated to show inferred location of Upper Mundic Gully TSF
Hydraulic properties and flow paths are described in section 5.6, 5.6.2 and figure 41
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Proposed conditioning (Table 7) states ‘Collection and monitoring of seepage within embankment.’ There is no detail or description regarding seepage from the structure, the volumes, or the management.
Table 7 Section 4.3.7
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Figure 40 of the application material depicts groundwater recharge zones, however it is unclear how the determination for the assumed recharge for upper mundic gully TSF has been derived as the figure doesn’t depict the proposed area clearly. Section 6.3.2 states impact to groundwater is unlikely due limited hydraulic conductivity and recharge and references section 5.5, however, section 5.5. does not include detail or a description of the new TSF area
Figure 40
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Reference to Section 5.5 is an error. Document updated to reference the correct Section 5.6
Section 5.6
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