Att 3 - Landslide Risk Assessment

                                                                                        Job No: 23-458
                                                                                                Page 7

2.4 Geotechnical Site Walkover

A site inspection was undertaken to confirm the geological, geomorphology, fill conditions, and to assess
the likely hazard rating based on site features that contribute to the initiation of a landslide.

The slope stability walkover assessment was undertaken on October 17, 2023.

A site report and frequency analysis were undertaken during the visit. The site report is a standard form
that identifies the site features that contribute to the occurrence of a landslide.

The major site features relevant to this assessment for natural and man-made slopes are:

    1. Slope Angle: In general, the steeper the average surface slope angle, the higher the risk of
       slope instability. Slope angles were directly measured onsite as well as calculated based on the
       detailed survey plan;

    2. Slope Shape and Features: The shape of the slope provides an indication of the method of
       slope development and the materials below the surface. Concave shapes often indicate past
       movements;

    3. Engineering Properties of Sub-surface Materials: The engineering properties of the materials
       forming the subsurface profile contribute to the risk of slope instability. Most slope failures occur
       in soil-strength material, and deeper soils increase the likelihood of slope failure.

    4. The Concentration of Surface/Ground Water: Water is one of the most important factors in
       landslides' occurrence. The majority of slope failures occur during or following rainfall events
       when there is a combination of surface erosion and saturation of subsurface materials. The
       concentration of Groundwater: The presence of a high groundwater table can provide a similar
       long-term situation to a rainfall event and contribute to slope failure without a major rainfall event;

    5. Evidence of Instability: In many cases, slope failures occur due to the reactivation of previous
       landslides. The presence of features that indicate past slope instability provides evidence that
       could initiate future slope movement;

    6. Regional position on a hillside; and

    7. Site geology

    8. Cut depth;
    9. Cut batter angle;
    10. Cut batter support;
    11. Fill depth;
    12. Fill batter angle;
    13. Fill Batter Support;
    14. Type of fill;
    15. Wastewater, sewerage, etc;
    16. Stormwater disposal;
    17. Expandable/mechanical stormwater and drainage pipe connectors;
    18. Footing system;
    19. The foundation strata;
    20. In-ground tanks (any type); and
    21. Landscaping.

Additional observations onsite include:

    •   Minor distress of a small section of the block retaining wall;
    •   No groundwater or seepage was observed throughout the site;

                                                                                                Ref: 4602
                                                                           399 Sunrise Road, Tinbeerwah