OPW052025 Report - Part 2

Text Figure 13: Extract from Slope/W Analysis (Section B-B'- including adverse groundwater condition)

The key points from our analyses are summarised as follows:
▪    Unit weight and shear strength parameters adopted for the soil and weathered rock strata were
     estimated based on our interpretation of the geotechnical investigation data and were typically
     within the mid-range of values recommended for similar materials in Appendix D of Australian
     Standard AS4678-2002 Earth Retaining Structures.
▪    Analyses were undertaken for a range of entry and exit points to assess global slope instability for
     the subsurface conditions encountered during the investigation (as outlined above. The analyses
     returned acceptable FOS values of at least 1.5 for long term conditions, which also included
     considered of an adverse short term groundwater condition.
▪    Analysis indicates that the development would achieve the minimum FOS requirement of 1.5 (long-
     term conditions) for hillside developments as required by the SCC Landslide Hazard and Steep Land
     Overlay Code.
Our analyses indicate that an acceptable FOS against instability could be achieved for proposed
development and that there would be a Low Risk of slope instability affecting the proposed residence
subject to implementation of the recommendations outlined in Section 6.




Geotechnical Investigation & Slope Stability Assessment
9 April 2025 | 25050-001-Rev0                                                                               17