Appendix D - Geotechnical Report

5.4          Groundwater
No signs of groundwater seepage at the surface (‘springs’) were observed during our walk-over around
the proposed development areas, nor was groundwater encountered in any of the test pits during the
investigation, which extended on the downslope side to a maximum depth of 3.1 m BGL.
Additionally, the potential reservoir for groundwater would be limited because of the topographical high
point in close proximity to the south/south-west along Black Mountain Range Road.
It should be noted that groundwater conditions are expected to be reflective of prevailing weather
conditions, and seepage may develop following periods of prolonged or heavy rainfall (e.g. along
geological faults, degraded quartz veins or at the contact between the soil and the underlying
‘rockhead’).


5.5          Geotechnical Laboratory Test Results
Table 1 summarises the results of laboratory testing conducted on soil samples recovered from the
boreholes. Laboratory test certificates are attached in Appendix B.

Table 1: Summary of Soil Classification & Shrink-Swell Index Testing

                           Atterberg Limits                                         Percent
                                                                                    Fines (%)
                                                                                                 Shrink-
                                                                                    [material
              Depth                                                    Linear                    Swell
 Location                  Liquid Limit   Plastic Limit   Plasticity                passing
              (m BGL)                                                  Shrinkage                 Index Iss
                           (%)            (%)             Index (%)                 75 µm
                                                                       (%)                       (%)
                                                                                    sieve]


 TP2          0.2 – 0.3    57             30              28           9.5          95           -

 TP5          0.1 – 0.4    -              -               -            -            -            2.5

Atterberg limits and particle size distribution testing indicates that the residual soil sample tested from
test pit TP2 consisted of a high plasticity, silty clay, with a very high ‘fines’ content (95 %).
Shrink-Swell Index testing indicated an Iss value of 2.5 %, for the sample of residual soil from test pit TP5.
The residual soils at this site would therefore be expected to have a moderate to high potential for soil
reactivity to normal seasonal moisture content changes.




Geotechnical Investigation
10 June 2026 | 26073-001-Rev0                                                                                 12