25289-001-Rev0 - The Esplanade (1)-compressed

3.          Method of Investigation
3.1         Fieldwork
An experienced geotechnical engineer from Tectonic undertook a site walk-over survey on 24 September
2025 to visually assess indicators of past slope instability. The walk-over included assessment of soil
exposures, surface drainage conditions, topography, evidence of erosion or past instability, and
vegetation coverage/condition.
In conjunction with the walk-over survey, two hand auger boreholes (designated BH1 and BH2) were
drilled. Borehole BH1 was drilled within the garden bed along the eastern boundary of the site, whilst
borehole BH2 was drilled within the proposed building footprint in the western part of the site. In situ
testing utilising the DCP method was completed from surface adjacent to each borehole, and at selected
downhole depths. In addition, three standalone DCP tests were conducted, from near the crest of the
sand dune and further down the dune face, extending to depths of between 2.1 m and 2.9 m below
ground level (BGL). Hand augers were taken to practical refusal at depths of between 3 m and 4 m BGL,
with DCP testing extending below the bases of the boreholes to depths of up to 6.9 m BGL.
Boreholes were backfilled with drilling spoil and left slightly mounded at the ground surface. Disturbed
soil samples were recovered from the auger cuttings. The engineer was responsible for logging soil
profiles and maintaining investigation practices in accordance with AS1726 Geotechnical site
investigations, supervising in situ testing, and recovering samples.
Borehole and DCP reports are attached in Appendix A, together with explanatory notes. Test locations
are shown in Figure 1 and subsurface conditions are discussed in Section 4.4.


3.2         Geotechnical Laboratory Testing
One selected disturbed soil sample from borehole BH1 was dispatched to a NATA accredited laboratory
for geotechnical testing, which comprised a particle size distribution (PSD) test for soil classification
purposes. Geotechnical laboratory testing was undertaken in accordance with Australian Standard
AS1289 Method for Testing Soils for Engineering Purposes.
Laboratory test results are summarised in Section 4.6, and the test certificate is attached in Appendix B.




Geotechnical investigation
19 November 2025 | 25289-001-Rev0                                                                            3