RFI - Att 1 - Slope Stablility Assessement

        Text Figure 5: Residual clay and weathered mudstone exposed in track cutting to south




                 Text Figure 6: Residual clays exposed in earthworks around northern dams

The previous Tectonic boreholes encountered stiff, residual, silty clay of medium plasticity, grading to
hard clay from about 1 m BGL.
The Wagner Level 1 report indicated that the fill used to construct the northern side of Dam 01,
estimated not more than 2 m high above the original ground surface, was compacted to a Hilf density
ratio of at least 95% Standard, and that the fill may be considered ‘controlled’.

2.2      Topography
Ground surface contours across the site and surrounds are illustrated in Text Figure 7 overleaf. The
existing and proposed dams are located within a natural drainage line, which is bounded by a spur within
the property to the eastern side (upon which the existing house and outbuildings are situated). The head
of the natural drainage line forms a broad gully within the south-western part of the subject site.
The original natural ground surface within the dam areas had a convergent and linear shape, being
relatively consistent down slope and concave across slope, however with a waning gradient approaching
the northern property boundary. No features indicative of previous landslide movement were observed
on the site; i.e. there were no backscarps, areas of ‘hummocky’ ground, tension cracks or the like.
Ground slope angles were estimated from measurements on site during the walk-over using a hand-held
clinometer. Inferred natural ground surface gradients ranged up to about 7° along the alignment of the


18 March 2026
25029-002-Rev0                                                                                      5 of 12