Appendix D - Geotechnical Report

3.           Aims & Method of Investigation
The main aims of the investigation were to address potential geotechnical constraints for the proposed
subdivision, along with an assessment of slope stability. It is understood that this report will be
submitted to Noosa Council (NC) in support of a Development Application for Reconfiguration of a Lot.
The investigation and report have therefore been designed to address the requirements of the relevant
NC codes and policies. However, it should be noted that this report only covers geotechnical matters to
address relevant parts of the NC Landslide Hazard Overlay Code and does not consider any other
requirements of the Code (e.g. site aesthetics, scenic amenity etc.).


3.1          Fieldwork
An experienced engineering geologist from Tectonic undertook a site walk-over on 3 March 2026 to
visually assess indicators of past slope instability. The walk-over included assessment of soil and rock
outcrops, surface drainage, topography, evidence of erosion, vegetation, and condition of structures.
This was incorporated with a subsurface investigation, which comprised the excavation of eight test pits
(designated TP1, TP2, TP3A, TP3B to TP7) supervised by a geotechnical engineer from Tectonic. The test
pits were undertaken using a 5.5 tonne excavator with a toothed bucket and ripper attachments to
depths between 1.2 m and 3.1 m below ground level (BGL), across the proposed development areas.
In situ soil strength was assessed using dynamic cone penetrometer (DCP) testing from surface adjacent
to each test pit (other than TP7), and using a pocket penetrometer (PP) on undisturbed U50 tube
samples, relatively undisturbed clayey block samples and test pit sidewalls (where safe to enter).
Disturbed samples were recovered from select test pits.
The test pits were backfilled progressively on completion, with excavation spoil left slightly mounded at
the surface. Co-ordinates were obtained using a handheld GPS unit with a recorded accuracy of ±3 m.
The test pits reports, along with explanatory notes, are presented in Appendix A. Approximate test
locations are shown in Figure 1, attached at the end of this report.



4.           Laboratory Testing
An undisturbed U50 tube sample and a small disturbed sample were dispatched to a NATA accredited
laboratory for geotechnical testing. Laboratory testing was undertaken in accordance with Australian
Standard AS1289 Methods of Testing Soils for Engineering Purposes and comprised one Shrink-Swell Index
analysis and one Atterberg Limits and complimentary Particle Size Distribution (PSD) test.
Laboratory test results are discussed in Section 5.8. The full laboratory test certificates are attached in
Appendix B.




Geotechnical Investigation
10 June 2026 | 26073-001-Rev0                                                                                 3