— Extend geological mapping to the west of the ridge, beyond the immediate TSF area, to verify and refine interpretations from existing geological maps and confirm the continuity and strike of mapped units westward. — Identify and characterise fracturing, defects, and structural features within the Razorback Beds, including joints, faults, and zones of enhanced weathering, which may locally influence groundwater flow and seepage pathways. — Confirm the presence and spatial distribution of those geological/hydrostratigraphic units conceptualised in the 2004 and 2011 Robertson studies [3, 10], including saprolite zones and fractured bedrock, within the TSF area. A reconnaissance plan will be developed prior to undertaken the field campaign and its findings will be documented in a technical memorandum.
5.2.3
Groundwater monitoring bores
Additional groundwater monitoring bores are required to verify the hydrogeological conceptualisation and to improve definition of groundwater levels, hydraulic gradients, and vertical connectivity downgradient of the proposed TSF. Data collected from these bores will support validation and refinement of seepage assumptions, improve confidence in predicted seepage pathways, and enable progressive reassessment of groundwater and surface‑water risks to nearby receptors. Details of the proposed monitoring bores are presented in Table 5.1 and their proposed locations are shown in Figure 5.1. These will be confirmed once the access and logistics have been confirmed upon completing a site reconnaissance. Hydraulic testing will be undertaken at the newly installed groundwater monitoring bores, subject to the geological conditions encountered during drilling. The testing program, consisting of packer tests, will be designed to characterise the hydraulic properties of the targeted hydrostratigraphic units, including the upper and basal sandstone units of the Razorback Beds and the underlying Paleozoic bedrock. In particular, testing will aim to estimate the overall permeability of each monitored unit and to identify higher‑permeability coarse‑grained or fractured intervals that may act as preferential groundwater and seepage pathways.
Table 5.1
Proposed additional groundwater monitoring bore details
Bore ID
Location
Justification
Target Hydrostratigraphic Unit
Estimated depth (m bgl)
Estimated screening depth (m bgl)
UMG-A1-MB1
Paddy Creek/Area 1
Characterise hydrostratigraphic units and provide monitoring along potential seepage pathway downgradient from TSF
RB – Upper Sandstone
59
51 - 57
UMG-A1-MB2
RB – Lower coarse Sandstone 81
76 - 79
UMG-A1-MB3
Paleozoic Bedrock
116
108 - 114
UMG-A2-MB1
Spring Creek/Area 2
RB – Upper Sandstone
52
44 - 50
UMG-A2-MB2
RB – Lower coarse Sandstone 74
69 - 72
UMG-A2-MB3
Paleozoic Bedrock
113
105 - 111
Final bore design, including screen depths and construction details, will be confirmed based on local geological conditions encountered during drilling and the specific monitoring objectives for each location, consistent with established groundwater monitoring standards and regulatory expectations.
Project No PS213278 Mount Morgan Mine - Upper Mundic Gully TSF Seepage Management Plan Heritage Minerals
WSP May 2026 Page 22
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